Derivative Financial Instruments - Fair Value of Derivative Financial Instruments and Their Classification on Balance Sheet (Details) (Interest rate contracts, USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Designated as Hedging Instrument | Other Assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 421	$ 197
Designated as Hedging Instrument | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	1,441	3,332
Not Designated as Hedging Instrument | Other Assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	3,054	6,103
Not Designated as Hedging Instrument | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	$ 3,136	$ 6,434