Condensed 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	$ 186,483	$ 178,871	$ 87,554
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	33,121	35,696	28,704
Provision for loan losses	12,777	13,783	11,890
Deferred income taxes	(1,492)	15,176	5,640
Revision of provisional amount related to the revaluation of deferred taxes from the Tax Reform Act		(991)	26,558
Other-than-temporary impairment on securities			753
(Gains) losses on sale of securities, net	(2,711)	655	(1,421)
Share-based compensation expense	8,839	8,783	6,934
Accretion of discount related to performing acquired loans	(12,986)	(27,756)	(15,893)
Loss on disposal of premises and equipment	3,617	1,568	177
(Gains) losses on sale of OREO	178	(1,969)	101
Net amortization of premiums on investment securities	7,260	7,567	6,853
OREO write downs	1,193	1,420	2,249
Fair value adjustment for loans held for sale	(1,057)	(521)	752
Originations and purchases of loans held for sale	(860,092)	(631,328)	(682,403)
Proceeds from sales of loans	824,712	679,811	745,871
Net change in:
Accrued interest receivable	(777)	(3,269)	(2,198)
Prepaid assets	(2,411)	1,951	6
Operating Leases	1,457
Miscellaneous other assets	(44,767)	(1,168)	(32,324)
Accrued interest payable	197	1,930	(948)
Accrued income taxes	(8,536)	143	1,959
Miscellaneous other liabilities	36,023	3,359	7,076
Net cash provided by operating activities	181,028	283,711	197,890
Cash flows from investing activities:
Proceeds from sales of investment securities available for sale	242,733	73,054	374,938
Proceeds from maturities and calls of investment securities held to maturity		2,530	3,570
Proceeds from maturities and calls of investment securities available for sale	308,109	224,713	235,757
Proceeds from sales of other investment securities	45	15,938	15,302
Purchases of investment securities available for sale	(955,505)	(191,313)	(241,274)
Purchases of other investment securities	(23,566)	(18,494)	(4,553)
Net increase in loans	(363,446)	(391,428)	(636,836)
Net cash received from acquisitions			185,163
Recoveries of loans previously charged off	3,914	3,300	3,430
Purchases of premises and equipment	(15,798)	(14,538)	(15,163)
Proceeds from sale of OREO	8,450	13,943	18,751
Proceeds from sale of premises and equipment	11	146	15
Net cash used in investing activities	(795,053)	(282,149)	(60,900)
Cash flows from financing activities:
Net increase in deposits	530,163	114,779	226,045
Net increase (decrease) in federal funds purchased and securities sold under agreements to repurchase and other short-term borrowings	28,092	(16,208)	(27,930)
Proceeds from other borrowings	700,001	590,001	100,000
Repayment of other borrowings	(150,007)	(540,007)	(390,811)
Common stock issuance	1,394	1,331	1,055
Common stock repurchases	(159,431)	(70,577)	(5,512)
Dividends paid on common stock	(57,696)	(50,557)	(38,623)
Stock options exercised	1,230	1,032	1,965
Net cash provided by (used in) financing activities	893,746	29,794	(133,811)
Net increase in cash and cash equivalents	279,721	31,356	3,179
Cash and cash equivalents at beginning of period	408,983	377,627	374,448
Cash and cash equivalents at end of period	688,704	408,983	377,627
Cash paid for:
Interest	86,355	52,062	17,962
Income taxes	55,674	31,941	48,028
Initial measurement and recognition of operating lease assets in exchange for lease liabilities per ASU 2016-02	82,160
Recognition of operating lease assets in exchange for lease liabilities	10,239
Acquisitions:
Fair value of tangible assets acquired		(7,247)	4,900,334
Other intangible assets acquired		3,321	44,295
Liabilities assumed		(612)	4,477,801
Net identifiable assets acquired over liabilities assumed		(3,314)	466,828
Common stock issued in acquisition			1,123,175
Loans sold that have not settled			28,663
Real estate acquired in full or in partial settlement of loans	$ 8,666	$ 13,391	$ 11,558