Long-Term Debt - Additional Information (Narrative) (Details) - USD ($)			12 Months Ended
	Apr. 15, 2014	Apr. 12, 2011	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Debt Instrument, proceeds from sale of Asset Limit or Repurchase offer given			$ 15,000,000
Senior Secured Notes
Debt Instrument [Line Items]
Interest rate			8.75%
Extinguishment of Debt, Amount	$ 50,000,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	25.00%
Interest expense on note			$ 13,100,000	$ 13,100,000	$ 14,300,000
Interest paid on notes			$ 13,100,000	$ 0
Private Placement | Senior Secured Notes
Debt Instrument [Line Items]
Private placement date		Apr. 12, 2011
Issuance of private placement, principal amount		$ 200,000,000.0
Interest rate		8.75%
Term of payments of interest on notes			semi-annually