Debt (Details)		12 Months Ended
	Mar. 20, 2013 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	May 25, 2011 CAD	May 25, 2011 USD ($)	Feb. 14, 2007
Debt Instrument [Line Items]
9½% Senior Notes		$ 250,000,000	$ 250,000,000
Credit Facility		0	0
Total debt outstanding		250,000,000	250,000,000
Unamortized debt issuance costs		(3,143,000)	(4,304,000)
Senior Notes, net of unamortized debt issuance costs		246,857,000	245,696,000
Interest		24,113,000	24,230,000	$ 24,132,000
Credit Facility
Maximum borrowing capacity						$ 30,000,000
Aggregate Maturities
Aggregate maturities of debt, 2017		0
Aggregate maturities of debt, 2018		0
Aggregate maturities of debt, 2019		250,000,000
Aggregate maturities of debt, 2020		0
Aggregate maturities of debt, 2021		$ 0
Canadian Lender [Member]
Credit Facility
Maximum borrowing capacity | CAD					CAD 5,000,000
Senior Notes [Member] | 9½% Senior Notes [Member]
Debt Instrument [Line Items]
Face amount of senior notes	$ 250,000,000
Interest rate of senior notes	9.50%
Call premium		101.00%
Accrued interest payable		$ 5,000,000	$ 5,000,000
Senior Notes [Member] | 9.75% Senior Notes [Member]
Debt Instrument [Line Items]
Interest rate of senior notes							9.75%
Cash on hand used to repurchase 9.75% Senior Notes	$ 29,800,000
Interest	$ 4,800,000