Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits
Change in benefit obligation:
Benefit obligation at beginning of year	$ 260,108	$ 274,874
Service cost		2,025	4,642
Interest cost	9,549	10,992	12,212
Actuarial (gain) loss	(28,749)	19,535
Amendments		5,473
Settlements		(14,560)
Curtailments		(28,192)
Benefits paid	(10,547)	(10,039)
Benefit obligation at end of year	230,361	260,108	274,874
Change in plan assets:
Fair value of plan assets at beginning of year	160,683	134,495
Actual return on plan assets	33,583	16,593
Employer Contribution	5,648	34,194
Settlements		(14,560)
Benefits paid	(10,547)	(10,039)
Fair value of plan assets at end of year	189,367	160,683	134,495
Funded status at end of year	(40,994)	(99,425)
Other Postretirement Benefits
Change in benefit obligation:
Benefit obligation at beginning of year	35,476	32,515
Service cost	1,578	1,061	529
Interest cost	1,279	1,378	1,360
Actuarial (gain) loss	(18,572)	1,454
Benefits paid	(995)	(932)
Benefit obligation at end of year	18,766	35,476	32,515
Change in plan assets:
Employer Contribution	995	932
Benefits paid	(995)	(932)
Funded status at end of year	$ (18,766)	$ (35,476)