CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
OPERATING ACTIVITIES:
Net income	$ 98,987,000	$ 74,324,000
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation	11,014,000	10,153,000
Deferred income and expense, net of amortization	(4,005,000)	(1,513,000)
Amortization of core deposit intangibles	4,112,000	4,790,000
Gain on sale of securities	(48,000)	(230,000)
Net change in valuation of financial instruments carried at fair value	(3,577,000)	1,831,000
Principal repayments and maturities of securities—trading	0	1,618,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges	249,000	0
(Increase) decrease in deferred taxes	7,044,000	(8,361,000)
Increase in current taxes payable	7,227,000	2,853,000
Stock-based compensation	4,844,000	4,232,000
Increase in cash surrender value of BOLI	(3,486,000)	(3,046,000)
Gain on sale of loans, net of capitalized servicing rights	(10,815,000)	(11,653,000)
Gain on disposal of real estate held for sale and property and equipment	(1,417,000)	(2,438,000)
Provision for loan losses	6,000,000	6,000,000
Provision for losses on real estate held for sale	187,000	256,000
Origination of loans held for sale	(637,702,000)	(626,677,000)
Proceeds from sales of loans held for sale	616,393,000	812,778,000
Net change in:
Other assets	521,000	(4,082,000)
Other liabilities	5,269,000	(144,000)
Net cash provided from operating activities	86,211,000	277,413,000
INVESTING ACTIVITIES:
Purchases of securities—available-for-sale	(668,456,000)	(706,911,000)
Principal repayments and maturities of securities—available-for-sale	123,132,000	135,163,000
Proceeds from sales of securities—available-for-sale	8,363,000	35,559,000
Purchases of securities—held-to-maturity	(8,469,000)	(5,105,000)
Principal repayments and maturities of securities—held-to-maturity	8,291,000	6,544,000
Loan originations, net of principal repayments	(214,487,000)	(211,539,000)
Purchases of loans and participating interest in loans	(5,487,000)	(111,148,000)
Proceeds from sales of other loans	6,629,000	9,456,000
Net cash paid related to branch divestiture	(20,412,000)	0
Purchases of property and equipment	(12,982,000)	(7,641,000)
Proceeds from sale of real estate held for sale and sale of other property, net	6,982,000	15,873,000
Proceeds from FHLB stock repurchase program	110,078,000	80,056,000
Purchase of FHLB stock	(118,940,000)	(88,404,000)
Other	3,562,000	327,000
Net cash used in investing activities	(782,196,000)	(847,770,000)
FINANCING ACTIVITIES:
Increase in deposits, net	523,047,000	417,436,000
Proceeds from FHLBank Advance, Investing Activities	0	150,000,000
Repayments of long-term Federal Home Loan Bank Advances	(8,000)	(7,000)
Proceeds from overnight and short term FHLB advances, net	221,000,000	59,000,000
Increase in other borrowings, net	3,119,000	(1,971,000)
Cash dividends paid	(46,989,000)	(57,467,000)
Taxes paid related to net share settlement of equity awards	1,364,000	1,187,000
Payments for Repurchase of Common Stock	15,359,000	1,400,000
Net cash provided from financing activities	683,446,000	564,404,000
NET CHANGE IN CASH AND CASH EQUIVALENTS	(12,539,000)	(5,953,000)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	261,200,000	247,719,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	248,661,000	241,766,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest paid in cash	18,901,000	13,406,000
Taxes paid, net	13,029,000	25,599,000
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	1,451,000	10,000
Dividends Payable	$ 12,654,000	$ 8,443,000