Deposits and Borrowed Funds (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Federal funds purchased, securities sold under repurchase agreements, and other short term borrowings
Balances at Year-end	$ 320,000		$ 1,214,200
Average Balance	1,247	514,100	52,051
Average interest rate (as a percent)	0.07%	0.18%	0.09%
Federal funds purchased.
Federal funds purchased, securities sold under repurchase agreements, and other short term borrowings
Balances at Year-end	320,000		1,214,200
Average Balance	1,247	301,086	52,051
Average interest rate (as a percent)	0.07%	0.13%	0.09%
Maximum month-end balance	320,000	943,000	1,214,200
Other short-term borrowings
Federal funds purchased, securities sold under repurchase agreements, and other short term borrowings
Average Balance		213,014
Average interest rate (as a percent)		0.26%
Maximum month-end balance		$ 950,000