Summary of Significant Accounting Policies (Details 9) - facility	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock-based compensation costs
Time period of historical volatility of stock used to estimate expected volatility	5 years 5 months 12 days
Expected dividend yield assumption (as a percent)	0.00%
Weighted-average assumptions used in the Black-Scholes option-pricing model
Risk-free interest rate (as a percent)	1.68%	1.08%	0.84%
Expected volatility (as a percent)	44.80%	46.27%	45.78%
Weighted-average expected life	5 years 5 months 12 days	6 years 6 months 26 days	6 years 7 months 21 days
Certain Risks and Uncertainties
Number of facilities in terms of net revenues that will face new significant competition in the near term	2
Number of facilities located in Charles Town, West Virginia that will face new significant competition in the near term	1
Number of facilities located in Grantville, Pennsylvania that will face new significant competition in the near term	1
Kansas
Segment Information
Ownership interest in joint venture (as a percent)	50.00%
Cordish
Segment Information
Ownership interest in joint venture (as a percent)	50.00%