Long-Term Debt - 6.75% Senior Notes due 2019 (Details) - 6.75% Unsecured Notes Due 2019 - USD ($)	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Debt Instrument [Line Items]
Senior note face amount	$ 350,000,000.0
Debt instrument interest rate	6.75%	6.75%	6.75%
Debt instrument maturity date	Mar. 01, 2019
Debt instrument frequency of periodic payment	semi-annually