Consolidated Statements of Cash Flow - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 222,539	$ 147,658	$ 98,291
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income tax expense	99,966	80,027	8,045
Amortization of investment premiums, net	23,544	20,822	32,663
Gain on sale of investment securities, net	(2,922)	(2,904)	(209)
Gain on sale of other real estate owned	(888)	(127)	(912)
Valuation adjustment on other real estate owned	2,782	3,728	2,160
Provision for loan and lease losses	36,589	40,241	10,716
Change in cash surrender value of bank owned life insurance	(8,501)	(9,713)	(4,280)
Change in FDIC indemnification asset	853	15,151	25,549
Depreciation, amortization and accretion	51,593	39,209	23,636
Loss on sale of premises and equipment	3,655	1,482	639
Increase in residential mortgage servicing rights	(35,284)	(23,311)	(17,963)
Change in residential mortgage servicing rights carried at fair value	20,726	16,587	(2,374)
Change in junior subordinated debentures carried at fair value	6,163	5,849	2,193
Stock-based compensation	14,383	15,292	5,017
Net decrease (increase) in trading account assets	413	452	(2,211)
Gain on sale of loans	(150,855)	(93,294)	(65,644)
Change in loans held for sale carried at fair value	696	(9,688)	14,503
Origination of loans held for sale	(3,497,920)	(2,146,829)	(1,599,683)
Proceeds from sales of loans held for sale	3,549,226	2,267,471	1,863,548
Excess tax benefits from the exercise of stock options	(556)	(1,626)	(65)
Change in other assets and liabilities:
Net decrease (increase) in other assets	25,248	(45,913)	31,902
Net increase (decrease) in other liabilities	15,290	38,632	(7,589)
Net cash provided by operating activities	376,740	359,196	417,932
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of investment securities available for sale	(1,074,205)	(363,064)	(51,191)
Purchases of investment securities held to maturity	0	0	(2,126)
Proceeds from investment securities available for sale	805,640	1,238,676	803,866
Proceeds from investment securities held to maturity	598	741	1,353
Redemption of restricted equity securities	72,442	5,615	2,758
Net change in loans and leases	(1,816,164)	(943,075)	(391,185)
Proceeds from sales of loans	288,805	356,464	63,042
Proceeds from insurance settlement on loss of property	0	0	575
Net change in premises and equipment	(69,341)	(59,514)	(34,224)
Proceeds from bank owned life insurance death benefit	5,351	3,723	1,173
Proceeds from redemption of bank owned life insurance cash surrender value	6,476	0	0
Net change in proceeds from FDIC indemnification asset	684	(2,667)	5,332
Proceeds from sales of other real estate owned	22,803	15,931	26,522
Net cash paid in divestiture	0	(127,557)	0
Net cash acquired (paid) in acquisition, net of consideration paid	0	116,867	(149,658)
Net cash used by investing activities	(1,756,911)	242,140	276,237
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in deposit liabilities	820,210	905,396	(261,184)
Net (decrease) increase in securities sold under agreements to repurchase	(8,761)	(496,307)	87,807
Proceeds from term debt borrowings	150,000	0	0
Repayment of term debt borrowings	(264,998)	(97,003)	(211,727)
Repayment of junior subordinated debentures	0	0	(8,764)
Dividends paid on common stock	(134,618)	(99,233)	(50,768)
Excess tax benefits from stock based compensation	556	1,626	65
Proceeds from exercise of stock options	925	6,116	6,398
Repurchases and retirement of common stock	(14,589)	(7,183)	(9,360)
Net cash provided (used) by financing activities	548,725	213,412	(447,533)
Net (decrease) increase in cash and cash equivalents	(831,446)	814,748	246,636
Cash and cash equivalents, beginning of year	1,605,171	790,423	543,787
Cash and cash equivalents, end of year	773,725	1,605,171	790,423
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest	67,884	55,235	40,826
Income taxes	13,263	7,098	41,993
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Change in unrealized losses on investment securities available for sale, net of taxes	(14,626)	16,987	(29,378)
Change in unrealized losses on investment securities held to maturity related to factors other than credit, net of taxes	0	57	56
Cash dividend declared on common stock and payable after period-end	35,281	33,109	16,936
Transfer of loans to other real estate owned	9,062	24,873	24,193
Transfer from FDIC indemnification asset to due from FDIC and other	2,709	3,606	4,075
Assets acquired	0	9,877,572	376,071
Liabilities assumed	$ 0	$ 8,767,025	$ 219,961