Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 146,920	$ 92,188	$ 90,930
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	6,810	7,550	7,530
Depreciation, amortization and accretion	3,496	4,832	3,091
Deferred income tax expense	16,444	23,461	11,037
Revaluation of net deferred tax assets due to changes in tax law	0	14,486	0
Funding of mortgage loans held for sale	(1,763,246)	(1,683,454)	(1,951,144)
Proceeds from sales of mortgage loans held for sale	1,698,141	1,775,450	2,031,036
Gains on sales of mortgage loans held for sale	(40,318)	(19,675)	(31,654)
Losses (gains) on sales of securities	16	(148)	(1,186)
Loss on extinguishment of debt	0	205	2,539
(Gains) losses on sales of premises and equipment	(198)	565	115
Stock-based compensation	7,251	5,293	3,117
Decrease in FDIC loss share indemnification asset, net of accretion and amortization	0	0	2,891
Loss on termination of FDIC loss share agreements	0	0	2,053
Decrease (increase) in other assets	44,044	(6,620)	10,136
Decrease in other liabilities	(41,954)	(12,572)	(16,694)
Net cash provided by operating activities	77,406	201,561	163,797
Investing activities
Purchases of securities available for sale	(686,887)	(210,190)	(140,133)
Proceeds from sales of securities available for sale	2,387	495,340	4,028
Proceeds from call/maturities of securities available for sale	160,703	169,445	158,359
Purchases of securities held to maturity	0	0	(15,267)
Proceeds from call/maturities of securities held to maturity	0	15,882	119,405
Net increase in loans	(115,208)	(440,205)	(504,640)
Purchases of premises and equipment	(22,360)	(13,047)	(13,560)
Proceeds from sales of premises and equipment	921	2,101	2,462
Proceeds from sales of other assets	8,361	14,131	16,939
Payment made to FDIC to terminate loss share agreements	0	0	(4,849)
Net cash received in acquisition	153,502	41,685	25,263
Net cash (used in) provided by investing activities	(498,581)	75,142	(351,993)
Financing activities
Net increase in noninterest-bearing deposits	49,087	11,588	209,943
Net increase (decrease) in interest-bearing deposits	447,317	(88,717)	279,146
Net increase (decrease) in short-term borrowings	263,753	(19,862)	(314,952)
Proceeds from long-term debt	0	0	98,385
Repayment of long-term debt	(849)	(170,240)	(47,230)
Cash paid for dividends	(43,614)	(34,416)	(29,734)
Repurchase of shares in connection with stock repurchase program	(7,062)	0	0
Cash received on exercise of stock options	201	173	415
Excess tax benefits from exercise of stock options	0	0	2,771
Proceeds from equity offering	0	0	84,105
Net cash provided by (used in) financing activities	708,833	(301,474)	282,849
Net increase (decrease) in cash and cash equivalents	287,658	(24,771)	94,653
Cash and cash equivalents at beginning of year	281,453	306,224	211,571
Cash and cash equivalents at end of year	569,111	281,453	306,224
Supplemental disclosures
Cash paid for interest	66,706	36,888	25,871
Cash paid for income taxes	24,520	32,556	22,731
Noncash transactions:
Transfers of loans to other real estate	3,826	6,699	8,870
Financed sales of other real estate owned	531	773	2,070
Transfers of loans held for sale to loan portfolio	1,732	563	17,838
Common stock issued in acquisition of businesses	$ 434,519	$ 213,590	$ 55,290