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Convertible Notes (Schedule of Notes) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Aug. 16, 2013	Jul. 10, 2009	Jun. 29, 2009
Debt Instrument [Line Items]
Other assets	$ 2,749	$ 2,165
Total convertible notes	126,167	119,418
Less current portion	0	0
Total long-term convertible notes	126,167	119,418
Convertible notes \| 1.125% Convertible Senior Notes due 2018
Debt Instrument [Line Items]
Face Value	138,000	138,000	$ 138,000
Unamortized discount	(10,913)	(17,099)
Unamortized Debt Issuance Expense	$ 920	1,483
Convertible notes \| 5% Convertible Senior Notes due 2014
Debt Instrument [Line Items]
Face Value				$ 22,500	$ 150,000
Adjustments for New Accounting Pronouncement [Member]
Debt Instrument [Line Items]
Other assets		2,165
Total long-term convertible notes		119,418
Adjustments for New Accounting Pronouncement [Member] \| Scenario, Previously Reported [Member]
Debt Instrument [Line Items]
Other assets		3,648
Total long-term convertible notes		120,901
Adjustments for New Accounting Pronouncement [Member] \| Scenario, Adjustment [Member]
Debt Instrument [Line Items]
Other assets		(1,483)
Total long-term convertible notes		$ (1,483)