Employee Benefits (Schedule of Net Funded (Unfunded) Status) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Change in Benefit Obligation:
Curtailment		$ (4,400)
Qualified Pension Plan [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period	61,162	70,615
Service cost	2,152	2,720	2,574
Interest cost	2,891	2,883	2,823
Actuarial loss (gain)	11,081	(8,809)
Benefits paid	(3,981)	(2,004)
Administrative expenses	(156)	(182)
Curtailment	0	(4,061)
Benefit obligation at end of period	73,149	61,162	70,615
Change in Plan Assets:
Fair value of plan assets at beginning of period	62,060	51,078
Actual return on plan assets	3,690	8,168
Employer contributions	6,000	5,000
Benefits paid	(3,981)	(2,004)
Administrative expenses	(156)	(182)
Fair value of plan assets at end of period	67,613	62,060	51,078
(Unfunded) funded status at end of period	(5,536)	898
Non-Qualified Retirement Plans [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period	10,784	12,569
Service cost	46	181	150
Interest cost	478	462	503
Actuarial loss (gain)	2,546	(1,332)
Benefits paid	(757)	(736)
Administrative expenses	0	0
Curtailment	0	(360)
Benefit obligation at end of period	13,097	10,784	12,569
Change in Plan Assets:
Fair value of plan assets at beginning of period	0	0
Actual return on plan assets	0	0
Employer contributions	757	736
Benefits paid	(757)	(736)
Administrative expenses	0	0
Fair value of plan assets at end of period	0	0	0
(Unfunded) funded status at end of period	$ (13,097)	$ (10,784)