401(k) Plan (Details) (USD $) In Millions, unless otherwise specified	4 Months Ended	8 Months Ended	12 Months Ended	30 Months Ended	32 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended
	Apr. 30, 2010 401(k) Plan	Dec. 31, 2010 401(k) Plan	Dec. 31, 2011 401(k) Plan	Jun. 13, 2009 401(k) Plan Y	Dec. 31, 2012 401(k) Plan Y	Dec. 31, 2012 Supplemental 401(k) Plan and the Safe Harbor 401(k) Plan Maximum	Dec. 31, 2012 Supplemental 401(k) Plan	Jan. 31, 2012 Safe Harbor 401(k) Plan	Dec. 31, 2012 Safe Harbor 401(k) Plan
Defined Contribution Plan Disclosure
Required completed period of service to become eligible to participate in plan (in years)				1	1
Minimum age requirement for employees to participate in plan (in years)				21	21
Employer match of employee contributions on first level of eligible compensation (as a percent)					50.00%			100.00%
Percentage of eligible compensation, first level, matched by employer					6.00%			3.00%
Employer match of employee contributions on second level of eligible compensation (as a percent)								50.00%
Percentage of eligible compensation, second level, partially matched by employer								2.00%
Employer matching contribution as a percentage of employee's base salary and bonus compensation						4.00%
Defined contribution expense recognized (in dollars)	$ 0.1	$ 1.6	$ 1.5				$ 3.0		$ 2.7