Portfolio Loans Covered by Loss Share ("Covered") - Summary of Changes in Accretable Yield for Purchased Loans (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of Changes in Accretable Yield for Purchased Loans [Roll Forward]
Balance at beginning of period	$ 63,335,000	$ 46,460,000
Additions	0	40,380,000
Accretion	(47,802,000)	(23,792,000)
Reclassifications from nonaccretable difference	68,817,000	9,137,000
Other	(5,582,000)	(8,850,000)
Balance at end of period	78,768,000	63,335,000	46,460,000
Loans Purchased From FDIC Outstanding Balance	301,200,000	496,200,000
Net cash proceeds received from FDIC loss share receivable	$ 91,641,000	$ 41,415,000	$ 5,009,000