CONSOLIDATED INCOME STATEMENTS - USD ($) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Interest income:
Loans, including fees	$ 3,679,800	$ 3,629,100	$ 3,409,700
Investment securities	815,900	703,600	459,900
Dividends and other	197,200	208,400	165,700
Total interest income	4,692,900	4,541,100	4,035,300
Interest expense:
Deposits	1,537,800	1,600,200	1,142,600
Qualifying debt	32,800	38,000	37,900
Other borrowings	257,500	284,000	515,900
Total interest expense	1,828,100	1,922,200	1,696,400
Net interest income	2,864,800	2,618,900	2,338,900
Provision for (recovery of) credit losses	224,100	145,900	62,600
Net interest income after provision for credit losses	2,640,700	2,473,000	2,276,300
Non-interest income:
Service charges and fees	194,300	109,600	110,300
Net gain on mortgage loan origination and sale activities	255,500	206,300	193,500
Net loan servicing revenue	77,800	121,500	102,300
Income from equity investments	18,100	38,200	15,700
Income from bank owned life insurance	46,000	27,800	4,500
Gain (loss) on sales of investment securities	29,400	17,400	(40,800)
Fair value gain (loss) adjustments, net	12,900	7,500	(116,000)
Other income	44,200	14,900	11,200
Non-interest income	678,200	543,200	280,700
Non-interest expense:
Salaries and employee benefits	757,500	631,100	566,300
Deposit costs	630,500	693,200	436,700
Insurance	117,500	164,800	190,400
Data processing	187,200	149,700	122,000
Legal, professional, and directors' fees	115,900	109,400	107,200
Occupancy	70,600	73,100	65,600
Loan servicing expenses	69,200	68,100	58,800
Business development and marketing	28,700	32,700	21,800
Loan acquisition and origination expenses	26,200	21,500	20,400
Extinguishment of debt	0	0	(52,700)
Other non-interest expense	108,400	81,400	86,900
Total non-interest expense	2,111,700	2,025,000	1,623,400
Income (loss) before provision for income taxes	1,207,200	991,200	933,600
Income tax expense	216,600	203,500	211,200
Net income	990,600	787,700	722,400
Net income attributable to noncontrolling interest	21,600	0	0
Net income attributable to Western Alliance	969,000	787,700	722,400
Dividends on preferred stock	12,800	12,800	12,800
Net income available to common stockholders	$ 956,200	$ 774,900	$ 709,600
Earnings per share:
Earnings per share, basic (dollars per share)	$ 8.79	$ 7.14	$ 6.55
Earnings per share, diluted (dollars per share)	$ 8.73	$ 7.09	$ 6.54
Weighted average number of common shares outstanding:
Weighted average number of common shares outstanding, basic (shares)	108.8	108.6	108.3
Weighted average number of common shares outstanding, diluted (shares)	109.5	109.3	108.5
Dividends declared per common share
Dividends declared per common share (dollars per share)	$ 1.56	$ 1.49	$ 1.45