Stock-Based Compensation - Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended							6 Months Ended				18 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2011	Dec. 31, 2007 2005 Stock Plan [Member]	Jun. 30, 2012 2011 Equity Incentive Award Plan [Member]	Dec. 31, 2011 2011 Equity Incentive Award Plan [Member]	May 09, 2011 2011 Equity Incentive Award Plan [Member]	Jun. 30, 2012 Stock Options [Member]	Jun. 30, 2011 Stock Options [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jun. 30, 2011 Restricted Stock [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jun. 30, 2012 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2012 Performance Shares Awards [Member]	Jun. 30, 2012 Performance Shares Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issue (in shares)				2,500,000			3,000,000
Shares available for future issuance (in shares)					2,794,172	3,336,614
Award vesting percentage per year (as a percent)										25.00%			25.00%
Grants in period (in shares)								0	0
Award vesting period								4 years
Contractual term								10 years
Issuance window after award vesting															60 days
Share-based compensation cost	$ 1.7		$ 0.2
Potential vesting percentage, minimum (as a percent)															0.00%
Potential vesting percentage, maximum (as a percent)															200.00%
Period used to determine weighted average volatility		2 years 9 months
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Volatility Analysis Lookback Period														2 years 9 months
Total unrecognized cost, period for recognition (in years)											2 years 6 months	3 years 3 months 18 days			2 years 6 months 4 days
Total unrecognized compensation cost										$ 6.3	$ 1.7	$ 6.3		$ 7.8	$ 7.8