Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended			12 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2007 California Franchise Tax Board [Member]	Dec. 31, 2006 California Franchise Tax Board [Member]	Dec. 31, 2005 California Franchise Tax Board [Member]	Dec. 31, 2010 Internal Revenue Service (IRS) [Member]	Dec. 31, 2009 Internal Revenue Service (IRS) [Member]	Dec. 31, 2010 Canada Revenue Agency [Member]	Dec. 31, 2009 Canada Revenue Agency [Member]	Dec. 31, 2008 Canada Revenue Agency [Member]
Income Taxes [Line Items]
U.S. federal statutory rate		35.00%
Effective income tax rate	23.60%
Income before income taxes, domestic operations		$ 27.7	$ 22.5
Income before income taxes, foreign operations		50.0	38.5
Liabilities for uncertain income tax positions	33.7	33.7		30.1
Cash paid for income taxes		5.7
Prepaid tax payments	$ 2.3	$ 2.3		$ 11.0
Income Tax Examination, Year under Examination					2007	2006	2005	2010	2009	2010	2009	2008