Employee Benefits (Changes in Funded Status of Plan - Other Postretirment Benefit Plans) (Details) (Other Postretirement Benefit Plans, Defined Benefit, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Other Postretirement Benefit Plans, Defined Benefit
Change in projected benefit obligation:
Benefit obligation at end of prior year	$ 133,272		$ 95,254
Service cost	4,378		2,988		3,558
Interest cost	5,651		5,379		6,664
Actuarial loss	(5,009)		32,694
Benefits paid	(3,929)		(4,180)
Retiree contributions	1,086		941
Medicare Part D subsidy	231		196
Benefit obligation at end of year	135,680		133,272		95,254
Change in plan assets:
Fair value of plan assets at end of prior year	32,817		33,660
Actual return on plan assets	2,605		0
Employer contribution	3,700		2,200
Benefits paid	(3,929)		(4,180)
Retiree contributions	1,086		941
Medicare Part D subsidy	231		196
Fair value of plan assets at end of year	36,510		32,817		33,660
Funded status	$ (99,170)	[1]	$ (100,455)	[1]

[1] These amounts are recognized in the Company’s consolidated balance sheets as a non-current liability.