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, 2015		74,530			8,636
Balance, beginning of period at Dec. 31, 2015	$ 3,267,639	$ 4	$ 982,009	$ 2,704,121	$ (477,165)	$ 21,587	$ 3,230,556	$ 37,083
Net income	232,281			232,668			232,668	(387)
Other comprehensive loss	(32,554)					(32,554)	(32,554)
Repurchase of common stock (in shares)					1,005
Repurchase of common stock	(66,792)				$ (66,792)		(66,792)
Stock options exercised (in shares)		214
Stock options exercised	12,465		12,465				12,465
Non-vested shares awarded, net (in shares)		249
Non-vested shares awarded,net	1,590		1,590				1,590
Vesting of non-vested shares (in shares)					15
Vesting of non-vested shares	(95)				$ (95)		(95)
Share-based compensation	10,471		10,471				10,471
Cash dividends on common stock	(113,455)			(113,455)			(113,455)
Capital calls and distributions, net	(5,193)							(5,193)
Balance, end of period (in shares) at Dec. 31, 2016		74,993			9,656
Balance, end 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 loss	(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
Non-vested shares awarded,net	0		0				0
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 net unrealized gains on equity securities	(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 loss	(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
Non-vested shares awarded,net			0
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)
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
Capital calls and distributions, net	(12,809)							(12,809)
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 net unrealized gains on equity securities	$ 2,700