Defined Contribution and 401(k) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Defined Contribution and 401(k) (Textual) [Abstract]
Total contribution by employees	$ 0.5	$ 0.4	$ 1.0	$ 0.8
Retirement Savings Plan under Section 401 (k) [Member]
Additional Defined Contribution And 401(k) (Textual) [Abstract]
Percentage of maximum limit for employees to contribute their cash compensation	100.00%
Percentage of employers matching contribution	100.00%
Percentage of employee contribution	3.00%
Percentage of employee compensation plus matching contribution	50.00%
Percentage of additional employee contribution	2.00%
Total plan expenses	$ 0.5	$ 0.3	$ 1.1	$ 0.6