Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 171,040	$ 189,589	$ 139,445
Adjustments to reconcile net income to net cash from operating activities:
Discount accretion, net amortization and depreciation	2,751	(2,128)	(14,903)
Stock-based compensation expense	5,282	3,659	3,161
Provision for loan losses	7,300	14,900	17,360
Credit for unfunded loan commitments	(100)	(100)	(2,358)
Valuation adjustment of premises held for sale	0	0	1,084
Valuation adjustment of OREO	(1,231)
Valuation adjustment of OREO		415	2,041
Impairment of investments in affordable housing partnership	0	0	4,846
Net gains on sales of SBA and other loans	(4,487)	(12,193)	(15,701)
Earnings on BOLI	(1,120)	(304)	(1,219)
Net change in fair value of derivatives	(71)	21	78
Net losses (gains) on sale and disposal of premises and equipment	75	50	(868)
Net losses (gains) on sales of OREO	14	(408)	(79)
Net gains on sales or called securities available for sale	(282)	0	(301)
Net change in fair value of equity investments with readily determinable fair value	(1,288)	(1,449)	0
Losses on investments in affordable housing partnership	9,137	11,728	10,266
Net change in deferred income taxes	1,535	2,742	34,740
Proceeds from sales of loans held for sale	116,590	266,115	310,345
Originations of loans held for sale	(103,819)	(255,545)	(276,537)
Origination of servicing assets	(1,790)	(6,157)	(5,874)
Change in accrued interest receivable	1,453	(2,246)	(3,099)
Change in other assets	(23,157)	(6,138)	(1,987)
Change in accrued interest payable	2,436	15,413	5,098
Change in other liabilities	3,587	1,983	(1,999)
Net cash provided by operating activities	183,855	219,947	203,539
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of interest bearing deposits in other financial institutions	(19,853)	(10,533)	(30,477)
Redemption of interest bearing deposits in other financial institutions	20,100	16,495	21,313
Purchase of securities available for sale	(229,283)	(393,584)	(572,528)
Proceeds from matured, called, or paid-down securities available for sale	296,154	221,595	264,730
Proceeds from sales of securities available for sale	115,628	0	128,791
Proceeds from sale of equity investments	2,570	0	0
Purchase of equity investments	0	(1,434)	0
Proceeds from sales of other loans	123,322	21,716	417
Purchase of loans receivable	(126,345)	0	0
Net change in loans receivable	(205,624)	(983,720)	(564,536)
Proceeds from sales of OREO	3,197	6,667	14,802
Purchase of FHLB stock	(2,417)	0	(8,573)
Redemption of FHLB stock	8,471	4,315	761
Purchase of premises and equipment	(6,619)	(6,846)	(14,777)
Proceeds from sales and disposals of premises and equipment	0	45	5,084
Proceeds from BOLI death benefits	1,834	0	382
Investments in affordable housing partnerships	(17,958)	(22,181)	(12,342)
Net cash used in investing activities	(36,823)	(1,147,465)	(766,953)
CASH FLOWS FROM FINANCING ACTIVITIES
Net change in deposits	371,708	1,309,048	209,477
Proceeds from FHLB advances	1,155,000	130,000	1,420,000
Repayment of FHLB advances	(1,350,000)	(465,000)	(1,015,000)
Proceeds from federal funds purchased	0	0	69,900
Repayment of federal funds purchased	0	(69,900)	0
Proceeds from convertible notes, net of issuance fees	0	212,920	0
Purchase of treasury stock	(13,223)	(150,000)	0
Cash dividends paid on common stock	(70,935)	(71,631)	(67,661)
Issuance of additional stock pursuant to various stock plans	12	469	1,865
Taxes paid in net settlement of restricted stock	(633)	(782)	(501)
Net cash provided by financing activities	91,929	895,124	618,080
NET CHANGE IN CASH AND CASH EQUIVALENTS	238,961	(32,394)	54,666
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	459,606	492,000	437,334
CASH AND CASH EQUIVALENTS, END OF YEAR	698,567	459,606	492,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest paid	211,014	144,128	91,081
Income taxes paid	57,115	57,862	104,158
SUPPLEMENTAL DISCLOSURES OF NON-CASH ACTIVITIES
Transfer of investments available for sale and other investments to equity investments	0	46,952	0
Transfer from loans receivable to OREO	19,381	3,340	7,173
Loans transferred to held for sale from loans receivable	165,994	21,581	429
Loans transferred to loans receivable from held for sale	5,181	10,073	4,100
Transfer from premises and equipment to premises held for sale	0	0	3,300
Loans to facilitate sale of premises	0	0	1,350
Loans to facilitate sale of OREO	0	0	2,300
New commitments to fund affordable housing partnership investments	0	30,097	26,400
Lease liabilities arising from obtaining right-of-use assets	62,833	0	0
Equity component of convertible notes, net of tax	$ 0	$ 15,045	$ 0