CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Statement of Cash Flows [Abstract]
Net cash paid related to branch divestiture	$ 0	$ 20,412
Gain (Loss) on Sale of Assets and Asset Impairment Charges	0	249
OPERATING ACTIVITIES:
Net income	73,046	61,214
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation	8,747	7,253
Deferred income and expense, net of amortization	(647)	(1,518)
Amortization of core deposit intangibles	4,105	2,764
Loss (gain) on sale of securities	27	(48)
Net change in valuation of financial instruments carried at fair value	103	(3,532)
Decrease (increase) in deferred taxes	(13,693)	6,510
Increase in current taxes payable	943	5,603
Stock-based compensation	3,394	3,231
Increase in cash surrender value of BOLI	(2,382)	(1,768)
Gain on sale of loans, net of capitalized servicing rights	(6,730)	(6,533)
Loss (gain) on disposal of real estate held for sale and property and equipment	721	(1,858)
Provision for loan losses	4,000	4,000
Provision for losses on real estate held for sale	0	160
Origination of loans held for sale	(397,227)	(415,790)
Proceeds from sales of loans held for sale	404,244	384,215
Net change in:
Other assets	(12,131)	1,734
Other liabilities	(5,911)	1,797
Net cash provided from operating activities	87,995	34,165
INVESTING ACTIVITIES:
Purchases of securities—available-for-sale	(52,525)	(591,265)
Principal repayments and maturities of securities—available-for-sale	120,638	69,853
Proceeds from sales of securities—available-for-sale	40,759	8,363
Purchases of securities—held-to-maturity	0	(8,469)
Principal repayments and maturities of securities—held-to-maturity	29,936	4,422
Loan originations, net of principal repayments	(64,641)	(82,461)
Purchases of loans and participating interest in loans	(777)	(2,268)
Proceeds from sales of other loans	7,155	4,733
Purchases of property and equipment	(11,759)	(9,925)
Proceeds from sale of real estate held for sale and sale of other property, net	4,243	6,367
Proceeds from FHLB stock repurchase program	90,373	79,878
Purchase of FHLB stock	(93,000)	(89,460)
Other	947	417
Net cash provided from (used in) investing activities	71,349	(630,227)
FINANCING ACTIVITIES:
(Decrease) increase in deposits, net	(188,081)	364,890
Proceeds from FHLBank Advance, Investing Activities	300,000	0
Repayments of long-term Federal Home Loan Bank Advances	(189)	(5)
(Repayment) proceeds from overnight and short term FHLB advances, net	(234,000)	239,000
(Decrease) Increase in other borrowings, net	(626)	16,598
Cash dividends paid	(27,906)	(19,494)
Taxes paid related to net share settlement of equity awards	1,869	1,343
Payments for Repurchase of Common Stock	32,073	15,359
Net cash (used in) provided from financing activities	(184,744)	584,287
NET CHANGE IN CASH AND CASH EQUIVALENTS	(25,400)	(11,775)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	272,196	261,200
CASH AND CASH EQUIVALENTS, END OF PERIOD	246,796	249,425
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest paid in cash	29,892	11,720
Tax paid, net	13,477	8,806
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	154	1,419
Dividends Payable	$ 14,714	$ 27,833