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, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2010
6% Convertible Guaranteed Note [Member]
Debt Instrument [Line Items]
Principal amount of debt component	$ 26,186,000		$ 28,991,000	$ 115,000,000
Unamortized discount	(1,244,000)		(1,500,000)
Carrying amount of debt component	24,942,000		27,491,000
Carrying amount of equity component	(27,564,000)		(26,032,000)
Effective interest rate	8.10%		8.10%
Aggregate if-converted value in excess of aggregate principal amount	16,045,000		14,296,000
Coupon interest	428,000	788,000
Discount amortization	121,000	223,000
Interest Expense	$ 549,000	$ 1,011,000