Condensed Parent Company Financial Statements (Detail) - Statements of Income (Parent Company Only) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income
Interest income		$ 287,247	$ 300,569	$ 321,511
Net losses on early extinguishment of debt	(1,034)	(1,034)	(558)	0
Securities transactions and other		4,452	7,086	3,114
Expenses
Interest expense		27,115	34,901	39,891
Other expenses		19,879	24,777	23,792
Income (loss) before income tax expense (benefit)		128,021	(49,936)	41,071
Income tax (expense) benefit		(48,715)	28,882	(4,508)
Net income (loss)		79,306	(21,054)	36,563
Net (income) loss applicable to non-vested restricted shares		1,107	(306)	350
Net income (loss) applicable to common shares		78,199	(20,748)	25,437
Parent Company
Income
Dividends from subsidiaries		54,200	38,000	104,000
Interest income		1,067	619	259
Net losses on early extinguishment of debt		(1,034)	(558)	0
Securities transactions and other		37,485	1,982	(189)
Total income		91,718	40,043	104,070
Expenses
Interest expense		13,607	14,840	9,892
Salaries and employee benefits		15,198	13,232	10,865
Other expenses		5,792	5,740	4,756
Total expenses		34,597	33,812	25,513
Income (loss) before income tax expense (benefit)		57,121	6,231	78,557
Income tax (expense) benefit		(962)	13,070	10,414
Income before undistributed income (loss) of subsidiaries		56,159	19,301	88,971
Equity in undistributed income (loss) of subsidiaries		23,147	(40,355)	(52,408)
Net income (loss)		79,306	(21,054)	36,563
Preferred dividends and accretion on preferred stock		0	0	(10,776)
Net (income) loss applicable to non-vested restricted shares		(1,107)	306	(350)
Net income (loss) applicable to common shares		$ 78,199	$ (20,748)	$ 25,437