Derivative Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Derivative Financial Instruments
Liability derivatives, Fair value	$ 134,592	$ 128,324
Non-hedging derivative financial instruments
Derivative Financial Instruments
Notional or contractual amount	508,989	482,576
Asset derivatives, Fair value	9,654	10,027
Liability derivatives, Fair value	9,721	10,094
Interest rate swap contracts
Derivative Financial Instruments
Asset derivatives, Fair value	10,065	10,511
Liability derivatives, Fair value	10,253	10,704
Interest rate swap contracts | Non-hedging derivative financial instruments
Derivative Financial Instruments
Notional or contractual amount	465,980	462,790
Asset derivatives, Fair value	9,531	9,894
Liability derivatives, Fair value	9,719	10,087
Loan commitments | Non-hedging derivative financial instruments
Derivative Financial Instruments
Notional or contractual amount	18,217	7,878
Asset derivatives, Fair value	122	12
Liability derivatives, Fair value	0	0
Forward contracts - mortgage loan | Non-hedging derivative financial instruments
Derivative Financial Instruments
Notional or contractual amount	23,650	10,600
Asset derivatives, Fair value	1	121
Liability derivatives, Fair value	0	0
Forward contracts - foreign exchange | Non-hedging derivative financial instruments
Derivative Financial Instruments
Notional or contractual amount	1,142	1,308
Asset derivatives, Fair value	0	0
Liability derivatives, Fair value	$ 2	$ 7