Income Taxes - Narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Expense (Benefit) [Abstract]
Effective income tax rate continuing operations	30.30%	34.30%
Federal statutory tax rate	35.00%
Effective Income Tax Rate, Prior to Recognition of Previously Unrecognized Tax Benefits	31.50%
Discrete tax benefits, primarily attributable to amending prior years' tax returns	$ 4.9
Gain on sale of offshore production system	19.6
Unremitted Earnings of Foreign Subsidiaries To Be Indefinitely Reinvested	132
Unrecognized Tax Benefits, Probability Threshold of Realizing for Tax Benefits Recognition, Minimum Percentage	50.00%
Penalties and interest expense relating to uncertain tax positions	0.4	0.2	0.5
Liabilities for penalties and interest on uncertain tax	4.4	4.0
Unrecognized Tax Benefits, Including Foreign Tax Credits and Penalties and Interest	$ 5.6