Derivative Financial Instruments - Offsetting Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Other Assets
Gross position	$ 25,410		$ 5,238
Impact of master netting agreement	(11,003)		(4,045)
Derivative values with impact of master netting agreements (as carried on balance sheet)	14,407		1,193
Cash collateral (held) pledged	(3,283)	[1]	(900)	[1]
Net position	11,124		293
Other Liabilities
Gross position	(38,063)		(28,688)
Impact of master netting agreement	11,003		4,045
Derivative values with impact of master netting agreements (as carried on balance sheet)	(27,060)		(24,643)
Cash collateral (held) pledged	58,625	[1]	72,478	[1]
Net position	$ 31,565		$ 47,835

[1] Cash collateral amount calculations include outstanding accrued interest payable/receivable.