Benefit Plans Benefit Plans - Summary of Benefit Plan (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Pension Benefits [Member]
Change in benefit obligation
Benefit obligation at beginning of year	$ 552,760		$ 490,544
Service cost	10,854		9,994		10,902
Interest cost	31,491		30,723		28,947
Actuarial loss	63,079		41,848
Plan participant contributions	0		0
Medicare retiree drug subsidy reimbursements	0		0
Benefits paid	(21,932)		(21,037)
Other	(42)		688
Benefit obligation at end of year	636,210		552,760		490,544
Change in plan assets
Fair value of plan assets at beginning of year	450,632		398,657
Actual return on plan assets	33,471		57,507
Employer contributions	23,318		15,505
Plan participant contributions	0		0
Benefits paid	(21,932)		(21,037)
Fair value of plan assets at end of year	485,489		450,632		398,657
Funded status
Funded status	(150,721)		(102,128)
Unrecognized net actuarial loss	213,712	[1]	152,854	[1]
Unrecognized prior service cost (benefit)	1,935	[1]	2,196	[1]
Prepaid (accrued) pension cost	64,926		52,922
Amounts recognized in balance sheets
Current liabilities	(2,846)		(2,711)
Noncurrent liabilities	(147,875)	[2]	(99,417)	[2]
Accumulated other comprehensive income	215,647		155,050		137,368
Net amount recognized	64,926		52,922
Change in accumulated other comprehensive income
Balance at beginning of year	155,050		137,368
Prior service (cost) credit recognized during the year	(259)		(197)
Net actuarial losses recognized during the year	(9,497)		(5,688)
Prior service cost occurring during the year	0		748
Net actuarial losses occurring during the year	70,353		22,819
Balance at end of year	215,647		155,050		137,368
Other Benefits [Member]
Change in benefit obligation
Benefit obligation at beginning of year	16,885		16,585
Service cost	0		0		1
Interest cost	930		993		1,127
Actuarial loss	1,277		1,311
Plan participant contributions	114		159
Medicare retiree drug subsidy reimbursements	177		219
Benefits paid	(2,361)		(2,382)
Other	0		0
Benefit obligation at end of year	17,022		16,885		16,585
Change in plan assets
Fair value of plan assets at beginning of year	0		0
Actual return on plan assets	0		0
Employer contributions	2,247		2,223
Plan participant contributions	114		159
Benefits paid	(2,361)		(2,382)
Fair value of plan assets at end of year	0		0		0
Funded status
Funded status	(17,022)		(16,885)
Unrecognized net actuarial loss	5,884	[1]	4,996	[1]
Unrecognized prior service cost (benefit)	(1,450)	[1]	(1,967)	[1]
Prepaid (accrued) pension cost	(12,588)		(13,856)
Amounts recognized in balance sheets
Current liabilities	(1,693)		(1,797)
Noncurrent liabilities	(15,329)	[2]	(15,088)	[2]
Accumulated other comprehensive income	4,434		3,029		1,485
Net amount recognized	(12,588)		(13,856)
Change in accumulated other comprehensive income
Balance at beginning of year	3,029		1,485
Prior service (cost) credit recognized during the year	517		517
Net actuarial losses recognized during the year	(389)		(284)
Prior service cost occurring during the year	0		0
Net actuarial losses occurring during the year	1,277		1,311
Balance at end of year	$ 4,434		$ 3,029		$ 1,485

[1] Represents amounts in accumulated other comprehensive income that have not yet been recognized as components of net periodic benefit costs.

[2] Included in the consolidated balance sheets in pensions and other benefits and other postretirement benefits are international plans.