Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net (loss) income	$ (47,156)	$ 485,397	$ 475,547
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
(Recoveries of) provisions for loan losses	(15,004)	(18,587)	30,758
Depreciation and amortization	31,497	27,792	28,092
Amortization of discounts and premiums, net	(8,069)	(8,293)	(3,600)
Amortization of core deposit intangibles	5,344	8,297	15,784
Net gain on sales of securities	(4,054)	(14,029)	(21,036)
Gain on sales of loans	(65,649)	(24,066)	(50,885)
Gain on Visa shares sold		(3,856)
Stock plan-related compensation	30,205	27,454	22,247
Deferred tax (benefit) expense	(31,289)	26,151	25,177
Loss on OTTI of securities recognized in earnings			612
Changes in operating assets and liabilities:
(Increase) decrease in other assets	(196,899)	105,575	(92,089)
Increase (decrease) in other liabilities	15,425	(16,020)	49,442
Origination of loans held for sale	(4,680,243)	(3,189,694)	(6,213,592)
Proceeds from sales of loans originated for sale	4,545,466	3,316,296	7,109,473
Net cash (used in) provided by operating activities	(420,426)	722,417	1,375,930
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from repayment of securities held to maturity	940,580	775,347	680,715
Proceeds from repayment of securities available for sale	9,889	9,787	59,362
Proceeds from sales of securities held to maturity	44,104	139,294	191,142
Proceeds from sales of securities available for sale	278,689	333,725	631,802
Purchase of securities held to maturity	(20,021)	(150,338)	(4,029,981)
Purchase of securities available for sale	(318,027)	(226,000)	(554,239)
Proceeds from sale of Visa shares		3,856
Net (purchase) redemption of Federal Home Loan Bank stock	(148,644)	46,063	(92,245)
Net increase in loans	(4,072,135)	(3,482,686)	(2,022,625)
Proceeds from sales of loans	1,923,208	478,605
Purchase of premises and equipment, net	(34,802)	(73,495)	(37,242)
Net cash used in investing activities	(1,397,159)	(2,145,842)	(5,173,311)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in deposits	98,024	2,667,742	783,471
Net increase (decrease) in short-term borrowed funds	768,100	(767,900)	2,466,100
Proceeds from long-term borrowed funds	11,243,500	50,000	2,460,312
Repayments of long-term borrowed funds	(10,489,682)	(160,615)	(3,251,601)
Tax effect of stock plans	2,486	3,225	1,692
Proceeds received from follow-on common stock offering, net	629,682
Cash dividends paid on common stock	(453,981)	(442,204)	(440,308)
Treasury stock purchases	(7,020)	(7,283)	(5,319)
Net cash received from stock option exercises		60	326
Net cash provided by financing activities	1,791,109	1,343,025	2,014,673
Net (decrease) increase in cash and cash equivalents	(26,476)	(80,400)	(1,782,708)
Cash and cash equivalents at beginning of year	564,150	644,550	2,427,258
Cash and cash equivalents at end of year	537,674	564,150	644,550
Supplemental information:
Cash paid for interest	540,818	553,811	552,501
Cash paid for income taxes	187,608	247,589	212,181
Cash paid for prepayment penalties on borrowings	914,965
Non-cash investing and financing activities:
Transfers to other real estate owned from loans	47,096	86,545	115,215
Transfer of loans from held for investment to held for sale	1,897,075	654,758
Transfer of loans from held for sale to held for investment	153,578
Shares issued for restricted stock awards	$ 7,708	$ 7,073	$ 5,093