The term "waiver" is sometimes used indiscriminately to refer to the doctrine of waiver, and the distinct but similar doctrine of estoppel. (DRG/Beverly Hills, Ltd. v. Chopstix Dim Sum Cafe & Takeout III, Ltd. (1994) 30 Cal. App. 4th 54, 59 35 Cal. Rptr. 2d 515.) "Waiver refers to the act, or the consequences of the act, of one side. Waiver is the intentional relinquishment of a known right after full knowledge of the facts and depends upon the intention of one party only. Waiver does not require any act or conduct by the other party." (Ibid.) Thus, "the pivotal issue in a claim of waiver is the intention of the party who allegedly relinquished the known legal right." (Id. at p. 60, italics added.) "Estoppel is applicable where the conduct of one side has induced the other to take such a position that it would be injured if the first should be permitted to repudiate its acts." (Id. at p. 59.) These distinctions between the two doctrines were reaffirmed in the insurance context in Waller v. Truck Ins. Exchange, Inc. (1995) 11 Cal. 4th 1 44 Cal. Rptr. 2d 370, 900 P.2d 619. The court in Waller stated: "Case law is clear that ' "waiver is the intentional relinquishment of a known right after knowledge of the facts." The burden . . . is on the party claiming a waiver of a right to prove it by clear and convincing evidence that does not leave the matter to speculation, and "doubtful cases will be decided against a waiver". The waiver may be either express, based on the words of the waiving party, or implied, based on conduct indicating an intent to relinquish the right." (Id. at p. 31.) Thus, "California courts will find waiver when a party intentionally relinquishes a right or when that party's acts are so inconsistent with an intent to enforce the right as to induce a reasonable belief that such right has been relinquished." (Id. at pp. 33-34, quoting Intel Corp. v. Hartford Acc. & Indem. Co. (9th Cir. 1991) 952 F.2d 1551, 1559.) The Waller court further observed that "in the insurance context the terms 'waiver' and 'estoppel' are sometimes used interchangeably, even though estoppel requires proof of the insured's detrimental reliance." (Waller v. Truck Ins. Exchange, Inc., supra, 11 Cal. 4th at p. 33.) "Whether there has been a waiver is usually regarded as a question of fact to be determined by the jury, or by the trial court if there is no jury." (Posner v. Grunwald-Marx, Inc. (1961) 56 Cal. 2d 169, 189 14 Cal. Rptr. 297, 363 P.2d 313.) By contrast, "the estoppel issue is a nonjury fact question to be determined by the trial court in accordance with applicable law." (DRG/Beverly Hills, Ltd. v. Chopstix Dim Sum Cafe & Takeout III, Ltd., supra, 30 Cal. App. 4th at p. 61.) However, the trial court may properly resolve an issue of waiver as a question of law when the underlying facts are undisputed. (Silva v. National American Life Ins. Co. (1976) 58 Cal. App. 3d 609, 615 130 Cal. Rptr. 211.)