Employee Benefits (Schedule of Net Funded (Unfunded) Status) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Qualified Pension Plan [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period	$ 73,149	$ 61,162
Service cost	2,459	2,152	$ 2,720
Interest cost	2,928	2,891	2,883
Actuarial (gain) loss	(5,410)	11,081
Benefits paid	(5,430)	(3,981)
Administrative expenses	(146)	(156)
Benefit obligation at end of period	67,550	73,149	61,162
Change in Plan Assets:
Fair value of plan assets at beginning of period	67,613	62,060
Actual return on plan assets	673	3,690
Employer contributions	3,000	6,000
Benefits paid	(5,430)	(3,981)
Administrative expenses	(146)	(156)
Fair value of plan assets at end of period	65,710	67,613	62,060
Unfunded status at end of period	(1,840)	(5,536)
Non-Qualified Retirement Plans [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period	13,097	10,784
Service cost	78	46	181
Interest cost	490	478	462
Actuarial (gain) loss	88	2,546
Benefits paid	(738)	(757)
Administrative expenses	0	0
Benefit obligation at end of period	13,015	13,097	10,784
Change in Plan Assets:
Fair value of plan assets at beginning of period	0	0
Actual return on plan assets	0	0
Employer contributions	738	757
Benefits paid	(738)	(757)
Administrative expenses	0	0
Fair value of plan assets at end of period	0	0	$ 0
Unfunded status at end of period	$ (13,015)	$ (13,097)