Long-Term Debt (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012		Jun. 30, 2013
2.25% Convertible Senior Notes due 2036 [Member]
Contractual interest expense and the discount amortization
Year-to-date contractual interest expense	$ 2,056		$ 2,056
Year-to-date discount amortization	3,404	[1]	3,689	[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	1,725		1,725
Year-to-date discount amortization	$ 1,449	[2]	$ 1,588	[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