Benefit Plans and Other Postretirement Benefits (Details 4) (Pension Benefits, USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure
Fair value of pension plan assets	$ 295,054	$ 296,530	$ 268,177
Equity securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	180,479	176,429
U.S. companies/securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	103,229	84,675
International companies/securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	77,250	91,754
Fixed income securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	111,490	106,696
U.S. securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	72,888	75,165
International securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	38,602	31,531
Cash and cash equivalents
Defined Benefit Plan Disclosure
Fair value of pension plan assets	3,085	13,405
Quoted prices for identical instruments in active markets (Level 1)
Defined Benefit Plan Disclosure
Fair value of pension plan assets	178,463	198,202
Quoted prices for identical instruments in active markets (Level 1) | Equity securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	120,980	128,090
Quoted prices for identical instruments in active markets (Level 1) | U.S. companies/securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	80,651	77,107
Quoted prices for identical instruments in active markets (Level 1) | International companies/securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	40,329	50,983
Quoted prices for identical instruments in active markets (Level 1) | Fixed income securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	54,398	56,707
Quoted prices for identical instruments in active markets (Level 1) | U.S. securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	54,398	56,707
Quoted prices for identical instruments in active markets (Level 1) | Cash and cash equivalents
Defined Benefit Plan Disclosure
Fair value of pension plan assets	3,085	13,405
Fair value Level 2
Defined Benefit Plan Disclosure
Fair value of pension plan assets	116,591	98,328
Fair value Level 2 | Equity securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	59,499	48,339
Fair value Level 2 | U.S. companies/securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	22,578	7,568
Fair value Level 2 | International companies/securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	36,921	40,771
Fair value Level 2 | Fixed income securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	57,092	49,989
Fair value Level 2 | U.S. securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	18,490	18,458
Fair value Level 2 | International securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	$ 38,602	$ 31,531