Defined Contribution and 401(k) (Details) (Retirement Savings Plan under Section 401 (k) [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Mar. 31, 2012	Sep. 30, 2013	Sep. 30, 2012
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	75.00%
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	$ 1.1	$ 1.0	$ 3.2	$ 3.1