Long-Term Debt (Details 2) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012
2.25% Convertible Senior Notes due 2036 [Member]
Contractual interest expense and the discount amortization
Year-to-date contractual interest expense	$ 3,084		$ 3,084
Year-to-date discount amortization	5,590	[1]	5,158	[1]
Effective interest rate of liability component	7.70%		7.70%
3.00% Convertible Senior Notes due 2020 [Member]
Contractual interest expense and the discount amortization
Year-to-date contractual interest expense	2,588		2,588
Year-to-date discount amortization	$ 2,410	[2]	$ 2,199	[2]
Effective interest rate of liability component	8.60%		8.60%

[1] Represents the incremental impact of the accounting for convertible debt as primarily codified in ASC 470, Debt.

[2] Represents the incremental impact of the accounting for convertible debt as primarily codified in ASC 470, Debt