Acquisitions (Activity for Acquired Loans) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	$ 68,305		$ 83,605
Additions, net of reductions	5,057	[1]	14,254	[1]
Accretion recognized in interest income	(23,972)		(29,804)
Reclassification from nonaccretable difference	0		250
Balance at end of period	$ 49,390		$ 68,305

[1] Represents an increase in estimated additional contractual interest expected to be collected as a result of maturing acquired loans that have been renewed or extended, net of a reduction in contractual interest resulting from the early payoff of acquired loans.