Retirement Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Number of retirement plans	2
Percentage of employer matching contribution on eligible earnings		70.00%
Additional contribution by employer		$ 0.5
401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of employer matching contribution on eligible earnings			1.00%
Additional contribution by employer	1.2
Percentage of additional matching contribution	127.00%
Total contributions under retirement plan	2.1	1.3	1.0
Registered Retirement Savings Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of employer matching contribution on eligible earnings	100.00%
Maximum employee earnings percentage matched by the Company	6.00%
Total contributions under retirement plan	$ 0.7	$ 0.6	$ 0.3