Share-based Compensation (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2013 Restricted Stock Units Executive officers	Mar. 31, 2013 Restricted Stock Units Outside directors	Mar. 31, 2013 Restricted Stock Units Outside directors Minimum	Mar. 31, 2013 Restricted Stock Units Outside directors Maximum	Jun. 30, 2013 Restricted Stock Units Employees
Restricted Stock information
Restricted stock units (RSUs) granted in period (in shares)					644,677	84,622			430,470
Fair value of restricted stock granted during the period (in dollars)					$ 4,100,000	$ 600,000			$ 2,700,000
Vesting period					3 years		1 year	3 years	3 years
Vesting subject to the grantees continued employment or providing service and reduction if the aggregate fair value of each grant exceeds a specified percentage of our Adjusted EBITDA (in shares)					212,384
Vesting subject to the grantees continued employment or providing service and certain revenue and Adjusted EBITDA growth targets (in shares)					432,293
Recognized compensation costs (in dollars)	3,247,000	4,439,000	9,672,000	13,816,000
Unrecognized compensation costs related to unvested options and RSUs (in dollars)	$ 17,600,000		$ 17,600,000
Weighted average remaining vesting period for recognition of compensation costs			1 year 8 months 12 days