Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 49,400	$ 46,365	$ 96,072	$ 91,564
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Provision for credit losses	5,000	5,000	9,500	10,000
Depreciation and amortization			24,232	25,834
Addition to (recovery of) valuation allowance on mortgage servicing rights, net			(465)	119
Amortization of mortgage servicing rights			6,147	5,545
Amortization of other intangible assets	888	991	1,689	1,982
Amortization and accretion on earning assets, funding, and other, net			19,457	13,788
Tax impact of stock based compensation			1,784	827
Gain on sales of investment securities, net	(1,242)	(34)	(1,242)	(412)	$ (494)
Gain on sales of assets and impairment write-downs, net	(1,893)	(899)	(2,989)	(1,627)
Gain on mortgage banking activities, net			(8,000)	(8,169)
Mortgage loans originated and acquired for sale			(619,202)	(479,449)
Proceeds from sales of mortgage loans held for sale			599,262	478,688
Increase (decrease) in interest receivable			808	(1,617)
Increase (decrease) in interest payable			5,596	(880)
Net change in other assets and other liabilities			(19,819)	(19,677)
Net cash provided by operating activities			112,830	116,516
CASH FLOWS FROM INVESTING ACTIVITIES
Net increase in loans			(703,636)	(1,166,685)
Purchases of:
Available for sale securities			(1,702,678)	(673,073)
Held to maturity securities			(133,976)	(70,581)
FHLB stock			(14,172)	(4,997)
Premises, equipment, and software, net of disposals			(26,232)	(19,365)
Other assets			(8,183)	(461)
Proceeds from:
Sales of available for sale securities	1,000,000		1,065,328	80,362	102,011
Sales of available for sale securities	43,000		42,514	0
Prepayments, calls, and maturities of available for sale securities			620,320	373,692
Prepayments, calls, and maturities of held to maturity securities			6,290	5,670
Prepayments, calls, and maturities of other assets			10,465	17,913
Net cash received in acquisition			1,132	0
Net cash used in investing activities			(842,828)	(1,457,525)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase in deposits			506,059	49,092
Net increase in short-term funding			527,248	1,596,245
Repayment of long-term funding			(1,000,017)	(155,018)
Proceeds from issuance of long-term funding			250,000	0
Purchase of common stock returned to authorized but unissued			(93,000)	0
Purchase of treasury stock			(4,500)	(72,647)
Proceeds from issuance of preferred stock			62,966	0
Purchase of preferred stock			(752)	(960)
Cash dividends on common stock			(30,508)	(29,175)
Cash dividends on preferred stock			(2,773)	(2,522)
Net cash provided by financing activities			214,723	1,385,015
Net increase (decrease) in cash and cash equivalents			(515,275)	44,006
Cash and cash equivalents at beginning of period			1,032,067	602,245	602,245
Cash and cash equivalents at end of period	516,792	646,251	516,792	646,251	1,032,067
Supplemental disclosures of cash flow information:
Cash paid for interest			32,123	26,971
Cash paid for income taxes			40,473	38,667
Loans and bank premises transferred to other real estate owned			3,117	12,049
Capitalized mortgage servicing rights			6,729	3,720	$ 8,253
Acquisition:
Fair value of assets acquired, including cash and cash equivalents	4,590	0	4,590	0
Fair value ascribed to goodwill and intangible assets	51,791	0	51,791	0
Fair value of liabilities assumed	$ 12,851	$ 0	12,851	0
Common stock issued in acquisition			$ 43,530	$ 0