Employee Benefit Plans (Details 4) (Supplemental Executive Retirement Plan (SERP), USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Executive Retirement Plan (SERP)
Amounts relating to the SERP that have been recognized in other comprehensive gain (loss)
Net unrecognized actuarial gain (loss)	$ 5,035	$ 3,956	$ (8,464)
Net unrecognized prior service cost	(2,627)	827	827
Total	2,408	4,783	(7,637)
Tax	(920)	(1,688)	2,807
Total, net of tax	1,488	3,095	(4,830)
Accumulated other comprehensive income (loss) that have not yet been recognized as a component of net periodic pension cost
Net unrecognized actuarial loss	2,767	7,803	11,758
Net unrecognized prior service cost	8,326	5,698	6,525
Total	11,093	13,501	18,283
Tax	(4,150)	(5,074)	(6,743)
Total, net of tax	6,943	8,427	11,540
Amounts included in accumulated other comprehensive income expected to be recognized as components of net periodic pension expense
Amortization of prior service cost	1,234
Total	$ 1,234