Loans and Allowance for Loan Losses (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Changes in allowance for loan losses
Balance at beginning of period	$ 70,222	$ 83,082	$ 76,510	$ 80,987
Loans charged-off	(4,293)	(5,940)	(12,121)	(17,193)
Recoveries of loans previously charged off	1,248	610	2,870	3,075
Net charge-offs	(3,045)	(5,330)	(9,251)	(14,118)
Provision for loan losses	109	(175)	27	10,708
Benefit attributable to FDIC loss share agreements	550	4,219	1,871	700
Total provision for loan losses charged to operations	659	4,044	1,898	11,408
Provision for loan losses recorded through the FDIC loss share receivable	(550)	(4,219)	(1,871)	(700)
Balance at end of period	67,286	77,577	67,286	77,577
Non-acquired loans
Changes in allowance for loan losses
Balance at beginning of period	38,625	47,269	44,378	49,367
Loans charged-off	(4,293)	(5,940)	(12,121)	(17,193)
Recoveries of loans previously charged off	1,248	610	2,870	3,075
Net charge-offs	(3,045)	(5,330)	(9,251)	(14,118)
Provision for loan losses	565	4,500	1,018	11,190
Total provision for loan losses charged to operations	565	4,500	1,018	11,190
Balance at end of period	36,145	46,439	36,145	46,439
Acquired loans
Changes in allowance for loan losses
Balance at beginning of period	31,597	35,813	32,132	31,620
Provision for loan losses	(456)	(4,675)	(991)	(482)
Benefit attributable to FDIC loss share agreements	550	4,219	1,871	700
Total provision for loan losses charged to operations	94	(456)	880	218
Provision for loan losses recorded through the FDIC loss share receivable	(550)	(4,219)	(1,871)	(700)
Balance at end of period	$ 31,141	$ 31,138	$ 31,141	$ 31,138