Debt Additional disclosures related to the 6.00% Convertible Guaranteed Notes due 2030 (Details) (6% Convertible Guaranteed Note [Member], USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2010
6% Convertible Guaranteed Note [Member]
Debt Instrument [Line Items]
Principal amount of debt component	$ 28,991,000		$ 28,991,000		$ 83,896,000	$ 115,000,000
Unamortized discount	(1,624,000)		(1,624,000)		(5,769,000)
Carrying amount of debt component	27,367,000		27,367,000		78,127,000
Carrying amount of equity component	(26,032,000)		(26,032,000)		3,654,000
Effective interest rate	8.10%		8.10%		8.10%
Aggregate if-converted value in excess of aggregate principal amount			18,621,000		42,579,000
Coupon interest	473,000	1,725,000	1,871,000	5,175,000
Discount amortization	137,000	484,000	534,000	1,453,000
Interest Expense	$ 610,000	$ 2,209,000	$ 2,405,000	$ 6,628,000