Debt (Parenthetical) (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Unamortized original issue discount	$ 15,656,000	$ 19,950,000
Senior Subordinated Convertible Notes 2010
Debt Instrument [Line Items]
Maturity period	Mar. 01, 2017
Interest rate on senior subordinated convertible notes	3.00%
2012 Credit Agreement | Revolving Loan
Debt Instrument [Line Items]
Amount available under revolving loan facility	$ 100,000,000
Maturity period	Nov. 09, 2017
2012 Credit agreement early termination date	Dec. 01, 2016
2012 Credit Agreement | Term Loan
Debt Instrument [Line Items]
Basis spread on term loan	2.00%
Term loan combined interest rate	2.24%	2.25%
Maturity period	Nov. 09, 2017
2012 Credit agreement early termination date	Dec. 01, 2016