Employee Benefit Plans (Projected Benefit Obligation) (Details) - SERP And Restoration Plans [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015
Change in projected benefit obligation:
Benefit obligation at beginning of period	$ 61,256		$ 32,259
Service costs	90		161
Interest costs	2,587		1,205
Actuarial (gains)/losses	1,817		(1,797)
Benefits paid	(2,989)		(1,880)
Defined Benefit Plan, Plan Amendments	2,347		0
Projected benefit obligation at end of period	65,108		61,256
Change in plan assets:
Plan assets at fair value at beginning of period	21,175		0
Benefits paid	(2,989)		(1,880)
Plan assets at fair value at beginning of period	25,225		21,175
Unfunded status of the plans	(39,883)		(40,081)
Accrued benefit liability	(65,108)		(61,256)
Pension plan asset	25,225		21,175
Amounts recognized in accumulated other comprehensive income/(loss):
Unrecognized net actuarial loss	14,021	[1]	11,363
Unrecognized prior service credit	(4,486)		(5,631)
Pension and other postretirement benefit plans, amount recognized in accumulated other comprehensive income	9,535		5,732
Change in Plan Assets [Member]
Change in projected benefit obligation:
Addition of RELS	0		21,175
Benefits paid	(2,989)		(1,880)
Change in plan assets:
Addition of RELS	0		21,175
Defined Benefit Plan, Actual Return on Plan Assets	(458)		0
Company contributions	7,497		1,880
Benefits paid	(2,989)		(1,880)
Projected Benefit Obligation [Member]
Change in projected benefit obligation:
Addition of RELS	0		31,308
Change in plan assets:
Addition of RELS	$ 0		$ 31,308

[1] The risk-free interest rate for the periods within the contractual term of the PBRSUs is based on the U.S. Treasury yield curve in effect at the time of the grant.