Debt and Other Financing Arrangements - Schedule of Note Interest Expense (Details) - Convertible Debt - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Contractual interest expense at 1.5% per annum	$ 3,795	$ 3,795	$ 3,795
Amortization of debt issuance costs	1,263	1,202	1,145
Accretion of debt discount	7,867	7,489	7,129
Total	$ 12,925	$ 12,486	$ 12,069