Senior Notes, Convertible Notes and Trust Preferred Securities - Narrative (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($) shares	Dec. 31, 2010 USD ($)	Dec. 31, 2007 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of notes required to be repurchased at the option of the holders on set dates				100.00%
Converted instrument, amount	$ 3,828,000	$ 12,763,000	$ 54,905,000
Issuance of common shares upon conversion of Convertible Notes (in shares) | shares	519,664	1,904,542	7,944,673
Repayments of convertible debt	$ 529,000	$ 233,000	$ 3,270,000
Debt satisfaction expense	476,000	2,436,000	$ 13,536,000
6.00% Convertible Guaranteed Note [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Face Amount	$ 12,400,000	16,228,000		$ 115,000,000
Debt interest rate percentage				6.00%
Convertible debt conversion ratio	0.1565514
Convertible debt conversion price | $ / shares	$ 6.39
6.804% Trust Preferred Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Face Amount					$ 200,000,000
Debt interest rate percentage					6.804%
Principal amount outstanding on Trust Preferred Securities	$ 129,120,000	$ 129,120,000
6.804% Trust Preferred Securities [Member] | London Interbank Offered Rate (LIBOR) [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Basis spread on variable rate					1.70%