Employee Benefit Plans (Details 5) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Mutual funds- equities and bonds
Fair value of plan assets by category
Fair value of plan assets	$ 43,900
Level 3 | Real estate funds / limited partnerships
Fair value of plan assets by category
Fair value of plan assets	12,025
U. S. Plans
Fair value of plan assets by category
Fair value of plan assets	209,237	221,673	216,919
U. S. Plans | Domestic equities - Common Stocks
Fair value of plan assets by category
Fair value of plan assets	39,295	52,930
U. S. Plans | Domestic equities - Mutual funds
Fair value of plan assets by category
Fair value of plan assets	40,107	59,049
U. S. Plans | International equities - mutual funds
Fair value of plan assets by category
Fair value of plan assets	37,740	26,354
U. S. Plans | U.S. Treasuries and collateralized securities
Fair value of plan assets by category
Fair value of plan assets	23,054	22,039
U. S. Plans | Corporate bonds and notes
Fair value of plan assets by category
Fair value of plan assets	5,507	9,920
U. S. Plans | Mutual funds - bonds
Fair value of plan assets by category
Fair value of plan assets	40,110	35,588
U. S. Plans | Other - mutual funds
Fair value of plan assets by category
Fair value of plan assets	19,392	12,375
U. S. Plans | Cash and money market accounts
Fair value of plan assets by category
Fair value of plan assets	4,032	3,418
U. S. Plans | Level 1
Fair value of plan assets by category
Fair value of plan assets	141,553	144,064
U. S. Plans | Level 1 | Domestic equities - Common Stocks
Fair value of plan assets by category
Fair value of plan assets	39,295	52,930
U. S. Plans | Level 1 | Domestic equities - Mutual funds
Fair value of plan assets by category
Fair value of plan assets	19	15,167
U. S. Plans | Level 1 | International equities - mutual funds
Fair value of plan assets by category
Fair value of plan assets	33,198	14,666
U. S. Plans | Level 1 | Corporate bonds and notes
Fair value of plan assets by category
Fair value of plan assets	5,507	9,920
U. S. Plans | Level 1 | Mutual funds - bonds
Fair value of plan assets by category
Fair value of plan assets	40,110	35,588
U. S. Plans | Level 1 | Other - mutual funds
Fair value of plan assets by category
Fair value of plan assets	19,392	12,375
U. S. Plans | Level 1 | Cash and money market accounts
Fair value of plan assets by category
Fair value of plan assets	4,032	3,418
U. S. Plans | Level 2
Fair value of plan assets by category
Fair value of plan assets	67,684	77,609
U. S. Plans | Level 2 | Domestic equities - Mutual funds
Fair value of plan assets by category
Fair value of plan assets	40,088	43,882
U. S. Plans | Level 2 | International equities - mutual funds
Fair value of plan assets by category
Fair value of plan assets	4,542	11,688
U. S. Plans | Level 2 | U.S. Treasuries and collateralized securities
Fair value of plan assets by category
Fair value of plan assets	23,054	22,039
International Plans
Fair value of plan assets by category
Fair value of plan assets	714,163	708,025	679,018
International Plans | Equity securities - Mutual funds
Fair value of plan assets by category
Fair value of plan assets	247,629	344,445
International Plans | Corporate bonds and notes
Fair value of plan assets by category
Fair value of plan assets		3,382
International Plans | Mutual funds - bonds
Fair value of plan assets by category
Fair value of plan assets	294,010	240,683
International Plans | Insurance contracts
Fair value of plan assets by category
Fair value of plan assets	63,169	57,324
International Plans | Other - mutual funds
Fair value of plan assets by category
Fair value of plan assets	63,568	18,832
International Plans | Real estate funds / limited partnerships
Fair value of plan assets by category
Fair value of plan assets	43,122	40,173
International Plans | Cash and money market accounts
Fair value of plan assets by category
Fair value of plan assets	2,665	3,186
International Plans | Level 1
Fair value of plan assets by category
Fair value of plan assets	2,665	149,507
International Plans | Level 1 | Equity securities - Mutual funds
Fair value of plan assets by category
Fair value of plan assets		119,864
International Plans | Level 1 | Corporate bonds and notes
Fair value of plan assets by category
Fair value of plan assets		1,038
International Plans | Level 1 | Mutual funds - bonds
Fair value of plan assets by category
Fair value of plan assets		25,419
International Plans | Level 1 | Cash and money market accounts
Fair value of plan assets by category
Fair value of plan assets	2,665	3,186
International Plans | Level 2
Fair value of plan assets by category
Fair value of plan assets	699,473	548,334
International Plans | Level 2 | Equity securities - Mutual funds
Fair value of plan assets by category
Fair value of plan assets	247,629	224,581
International Plans | Level 2 | Corporate bonds and notes
Fair value of plan assets by category
Fair value of plan assets		2,344
International Plans | Level 2 | Mutual funds - bonds
Fair value of plan assets by category
Fair value of plan assets	294,010	215,264
International Plans | Level 2 | Insurance contracts
Fair value of plan assets by category
Fair value of plan assets	63,169	57,324
International Plans | Level 2 | Other - mutual funds
Fair value of plan assets by category
Fair value of plan assets	63,568	18,832
International Plans | Level 2 | Real estate funds / limited partnerships
Fair value of plan assets by category
Fair value of plan assets	31,097	29,989
International Plans | Level 3
Fair value of plan assets by category
Fair value of plan assets	12,025	10,184
International Plans | Level 3 | Real estate funds / limited partnerships
Fair value of plan assets by category
Fair value of plan assets	$ 12,025	$ 10,184	$ 10,994