Debt - Additional disclosures related to the 6.00% Convertible Guaranteed Notes due 2030 (Details) (6% Convertible Guaranteed Note [Member], USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2010
6% Convertible Guaranteed Note [Member]
Debt Instrument [Line Items]
Principal amount of debt component	$ 15,628,000		$ 16,228,000	$ 115,000,000
Unamortized discount	(476,000)		(564,000)
Carrying amount of debt component	15,152,000		15,664,000
Carrying amount of equity component	(33,536,000)		(33,160,000)
Effective interest rate	8.10%		8.10%
Aggregate if-converted value in excess of aggregate principal amount	7,661,000		10,432,000
Coupon interest	236,000	428,000
Discount amortization	67,000	121,000
Interest expense	$ 303,000	$ 549,000