Senior Notes, Convertible Notes, Exchangeable Notes and Trust Preferred Securities - Schedule of Long-term Debt Instruments (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2007
6.00% Convertible Guaranteed Note [Member]
Debt Instrument [Line Items]
Debt interest rate percentage	6.00%	6.00%	6.00%	6.00%
Face Amount	$ 16,228,000	$ 28,991,000		$ 115,000,000
Unamortized discount	(564,000)	(1,500,000)
Carrying amount of debt component	15,664,000	27,491,000
Carrying amount of equity component	(33,160,000)	(26,032,000)
Effective interest rate	8.10%	8.10%
Aggregate if-converted value in excess of aggregate principal amount	10,432,000	14,296,000
Coupon interest	1,545,000	2,296,000	6,634,000
Discount amortization	438,000	658,000	1,868,000
Interest Expense	1,983,000	2,954,000	8,502,000
5.45% Exchangeable Guaranteed Note [Member]
Debt Instrument [Line Items]
Debt interest rate percentage					5.45%
Face Amount					450,000,000
Coupon interest	0	0	188,000
Discount amortization	0	0	34,000
Interest Expense	$ 0	$ 0	$ 222,000