Consolidated Statements of Changes in Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total Shareholders' Equity [Member]	Non-Controlling Interests [Member]
Balance, beginning of period (in shares) at Dec. 31, 2016		74,993			9,656
Balance, beginning of period at Dec. 31, 2016	$ 3,306,357	$ 4	$ 1,006,535	$ 2,823,334	$ (544,052)	$ (10,967)	$ 3,274,854	$ 31,503
Net income	335,685			334,644			334,644	1,041
Other comprehensive income (loss), net	(18,657)					(18,657)	(18,657)
Repurchase of common stock (in shares)					80
Repurchase of common stock	(7,403)				$ (7,403)		(7,403)
Stock options exercised (in shares)		100
Stock options exercised	5,758		5,758				5,758
Non-vested shares awarded, net (in shares)		55
Vesting of non-vested shares (in shares)					17
Vesting of non-vested shares	(1,390)				$ (1,390)		(1,390)
Share-based compensation	23,602		23,602				23,602
Cash dividends on common stock	(116,041)			(116,041)			(116,041)
Capital calls and distributions, net	(9,577)							(9,577)
Reclassification of stranded accumulated other comprehensive loss to retained earnings related to tax reform	(6,550)			6,550		(6,550)
Balance, end of period (in shares) at Dec. 31, 2017		75,148			9,753
Balance, end of period at Dec. 31, 2017	3,518,334	$ 4	1,035,895	3,048,487	$ (552,845)	(36,174)	3,495,367	22,967
Transition adjustment of new accounting principle	(2,709)			2,709		(2,709)
Balance, beginning of period, Adjusted	3,518,334	$ 4	1,035,895	3,051,196	$ (552,845)	(38,883)	3,495,367	22,967
Net income	446,424			445,646			445,646	778
Other comprehensive income (loss), net	(33,702)					(33,702)	(33,702)
Repurchase of common stock (in shares)					616
Repurchase of common stock	(53,465)				$ (53,465)		(53,465)
Stock options exercised (in shares)		54
Stock options exercised	2,781		2,781				2,781
Non-vested shares awarded, net (in shares)		109
Vesting of non-vested shares (in shares)					31
Vesting of non-vested shares	(2,870)				$ (2,870)		(2,870)
Share-based compensation	4,229		4,229				4,229
Cash dividends on common stock	(127,188)			(127,188)			(127,188)
Capital calls and distributions, net	(12,809)							(12,809)
Issuance of shares for CoBiz acquisition (in shares)		400			(6,811)
Issuance of shares fro CoBiz acquisition	701,311	$ 1	291,125		$ 410,185		701,311
Balance, end of period (in shares) at Dec. 31, 2018		75,711			3,589
Balance, end of period at Dec. 31, 2018	4,443,045	$ 5	1,334,030	3,369,654	$ (198,995)	(72,585)	4,432,109	10,936
Transition adjustment of new accounting principle	2,862			2,862			2,862
Balance, beginning of period, Adjusted	4,445,907	$ 5	1,334,030	3,372,516	$ (198,995)	(72,585)	4,434,971	10,936
Net income	500,685			500,758			500,758	(73)
Other comprehensive income (loss), net	177,508					177,508	177,508
Repurchase of common stock (in shares)					1,572
Repurchase of common stock	(129,483)				$ (129,483)		(129,483)
Stock options exercised (in shares)		27
Stock options exercised	1,421		1,421				1,421
Non-vested shares awarded, net (in shares)		21
Vesting of non-vested shares (in shares)					18
Vesting of non-vested shares	(1,428)				$ (1,428)		(1,428)
Share-based compensation	15,544		15,544				15,544
Cash dividends on common stock	(143,496)			(143,496)			(143,496)
Capital calls and distributions, net	(2,739)							(2,739)
Balance, end of period (in shares) at Dec. 31, 2019		75,759			5,179
Balance, end of period at Dec. 31, 2019	$ 4,863,919	$ 5	$ 1,350,995	$ 3,729,778	$ (329,906)	$ 104,923	$ 4,855,795	$ 8,124