Pension and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Change in Plan Assets:
Fair value of plan assets, end of year	$ 160,806
Amounts recognized in the balance sheets:
Postretirement benefits	(131,237)	(112,426)
Pension Benefits [Member]
Change in benefit obligation
Benefit obligation, beginning of year	(226,805)	(222,948)
Service cost	(5,863)	(4,994)	(4,949)
Interest cost	(11,687)	(11,508)	(12,163)
Participant contributions	(125)	(125)
Plan amendments	(356)
Actuarial loss	(10,855)	(7,637)
Other	(7)
Special termination benefits		(20)
Foreign currency exchange rate changes	44	4,935
Benefits paid	15,652	15,492
Benefit obligation, end of year	(240,002)	(226,805)	(222,948)
Change in Plan Assets:
Fair value of plan assets, beginning of year	160,364	143,491
Actual return on plan assets	7,074	18,628
Employer contributions	8,598	14,317
Participant contributions	125	125
Other	7
Foreign currency exchange rate changes	297	(705)
Benefits paid	(15,652)	(15,492)
Fair value of plan assets, end of year	160,806	160,364	143,491
Funded status, end of year	(79,196)	(66,441)
Amounts recognized in the balance sheets:
Prepaid benefit cost	9,501	6,920
Accrued benefit liability (current)	(3,896)	(4,022)
Postretirement benefits	(84,801)	(69,339)
Net funded status	(79,196)	(66,441)
Other Benefits [Member]
Change in benefit obligation
Benefit obligation, beginning of year	(45,917)	(44,232)
Service cost	(92)	(142)	(91)
Interest cost	(2,199)	(2,305)	(2,330)
Participant contributions	(3)	(12)
Actuarial loss	(4,262)	(553)
Other		(138)
Foreign currency exchange rate changes	525	(1,304)
Benefits paid	2,830	2,769
Benefit obligation, end of year	(49,118)	(45,917)	(44,232)
Change in Plan Assets:
Fair value of plan assets, beginning of year	0	0
Employer contributions	2,827	2,619
Participant contributions	3	12
Other		138
Benefits paid	(2,830)	(2,769)
Fair value of plan assets, end of year	0	0	0
Funded status, end of year	(49,118)	(45,917)
Amounts recognized in the balance sheets:
Prepaid benefit cost	0	0
Accrued benefit liability (current)	(2,682)	(2,830)
Postretirement benefits	(46,436)	(43,087)
Net funded status	$ (49,118)	$ (45,917)