Employee Benefit Plans Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax benefit	$ 36,889	$ 41,075
AOCI	(144,580)	(144,084)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service (cost) credit	(7,062)	(8,370)
Net losses	(191,813)	(191,761)
Deferred income tax benefit	61,968	62,797
AOCI	(136,907)	(137,334)
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service (cost) credit	193	167
Net losses	(11,939)	(10,500)
Deferred income tax benefit	4,073	3,583
AOCI	$ (7,673)	$ (6,750)