Loans (Changes in the carrying amount and accretable yield for covered loans) (Details) (Covered impaired loan, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Covered impaired loan
Changes in the carrying amount of accretable yield for covered loans [Line Items]
Certain Loans Acquired in Transfer, Accretable Yield	$ 37,511	$ 67,282	$ 113,288
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	232,452	403,692	762,386
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion	(42,161)	(64,528)
Certain Loans Acquired in Transfer not Accounted for as Debt Securities Carrying Amount Accretion	42,161	64,528
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference	16,841	34,965
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities F D I C Payments Received under Loss Sharing Agreement	(213,401)	(423,222)
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Disposals of Loans	$ (4,451)	$ (16,443)