Debt Schedule of Convertible Debt (Details) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Aug. 31, 2009 Senior Exchangeable Notes due 2015 at a fixed interest rate of 4.50% [Member]	Dec. 31, 2013 Senior Exchangeable Notes due 2015 at a fixed interest rate of 4.50% [Member]		Dec. 31, 2012 Senior Exchangeable Notes due 2015 at a fixed interest rate of 4.50% [Member]	Dec. 31, 2011 Senior Exchangeable Notes due 2015 at a fixed interest rate of 4.50% [Member]	Oct. 31, 2007 Senior Exchangeable Notes due 2012 at a fixed interest rate of 3.75% [Member]	Dec. 31, 2013 Senior Exchangeable Notes due 2012 at a fixed interest rate of 3.75% [Member]	Dec. 31, 2012 Senior Exchangeable Notes due 2012 at a fixed interest rate of 3.75% [Member]	Dec. 31, 2011 Senior Exchangeable Notes due 2012 at a fixed interest rate of 3.75% [Member]
Schedule of Convertible Debt [Line Items]
Principal amount of debt				$ 172,500,000.0	$ 130,973,000		$ 172,500,000		$ 300,000,000
Unamortized discount					(3,224,000)		(6,679,000)
Net carrying amount of debt	127,749,000	165,821,000
Common stock	8,850,000	8,850,000
Fixed interest rate				4.50%	4.50%	[1]			3.75%	3.75%
Maturity date description				August 2015	August 2015				October 2012
Contractual interest coupon					7,271,000		7,763,000	7,763,000		0	8,682,000	11,250,000
Amortization of debt discount	1,215,000	6,323,000	8,654,000		2,281,000		2,296,000	2,167,000		0	5,378,000	6,487,000
Total interest expense recognized	$ 9,552,000	$ 24,119,000	$ 27,667,000
Effective rate	6.21%	6.21%	6.21%

[1] Our Senior Exchangeable Notes maturing in 2015 were discounted by $3.2 million and $6.7 million as of December 31, 2013 and 2012, respectively, but upon maturity the liability will be $131 million.