CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Statement of Cash Flows [Abstract]
Net cash paid related to branch divestiture	$ 10,382	$ 20,412
OPERATING ACTIVITIES:
Net income	112,623	98,987
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation	12,934	11,014
Deferred income and expense, net of amortization	(350)	(4,005)
Amortization of core deposit intangibles	6,090	4,112
Loss (gain) on sale of securities	29	(48)
Net change in valuation of financial instruments carried at fair value	172	(3,577)
Decrease (increase) in deferred taxes	(16,136)	7,044
Increase in current taxes payable	3,410	7,227
Stock-based compensation	5,101	4,844
Increase in cash surrender value of BOLI	(3,086)	(3,486)
Gain on sale of loans, including capitalized servicing rights	(11,834)	(10,815)
Loss (gain) on disposal of real estate held for sale and property and equipment	1,274	(1,417)
Provision for loan losses	6,000	6,000
Provision for losses on real estate held for sale	0	187
Origination of loans held for sale	(756,283)	(637,702)
Proceeds from sales of loans held for sale	694,259	616,393
Net change in:
Other assets	(26,381)	521
Other liabilities	8,398	5,269
Net cash provided from operating activities	68,492	86,460
INVESTING ACTIVITIES:
Purchases of securities—available-for-sale	(118,823)	(668,456)
Principal repayments and maturities of securities—available-for-sale	209,396	123,132
Proceeds from sales of securities—available-for-sale	43,114	8,363
Purchases of securities—held-to-maturity	(42,350)	(8,469)
Principal repayments and maturities of securities—held-to-maturity	44,971	8,291
Loan originations, net of principal repayments	(158,754)	(218,226)
Purchases of loans and participating interest in loans	(8,608)	(1,748)
Proceeds from sales of other loans	16,279	6,629
Purchases of property and equipment	(16,738)	(12,982)
Proceeds from sale of real estate held for sale and sale of other property, net	6,809	6,982
Proceeds from FHLB stock repurchase program	130,073	110,078
Purchase of FHLB stock	(123,740)	(118,940)
Other	1,461	3,562
Net cash used in investing activities	(27,292)	(782,196)
FINANCING ACTIVITIES:
Increase in deposits, net	266,129	522,798
Proceeds from FHLBank Advance, Investing Activities	300,000	0
Repayments of long-term Federal Home Loan Bank Advances	(100,189)	(8)
(Repayment) proceeds from overnight and short term FHLB advances, net	(358,000)	221,000
Increase in other borrowings, net	1,019	3,119
Cash dividends paid	(42,073)	(46,989)
Taxes paid related to net share settlement of equity awards	1,904	1,364
Payments for Repurchase of Common Stock	53,922	15,359
Net cash provided from financing activities	11,060	683,197
NET CHANGE IN CASH AND CASH EQUIVALENTS	52,260	(12,539)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	272,196	261,200
CASH AND CASH EQUIVALENTS, END OF PERIOD	324,456	248,661
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest paid in cash	45,348	18,901
Tax paid, net of refunds	18,220	13,029
NON-CASH INVESTING AND FINANCING TRANSACTIONS:
Loans, net of discounts, specific loss allowances and unearned income, transferred to real estate owned and other repossessed assets	246	1,451
Dividends Payable	$ 14,679	$ 12,654