Debt and Financing Arrangements - Secured Floating Rate Notes (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Oct. 31, 2013	Oct. 31, 2011	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 20, 2012	Jul. 29, 2011
Debt Instrument [Line Items]
Aggregate principal amount						$ 4,500	$ 168,000
Proceeds from the issuance of notes			$ 375,000
Interest Expense			49,908	$ 60,294	$ 63,529
Secured Floating Rate Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 125,000	$ 500,000		375,000
Repayment of debt	150,000
Issuance cost	2,300	$ 13,200		2,200
Interest Expense	1,000
Issuance cost incurred	$ 3,300
Interest expense, including amortization of debt issuance costs			$ 12,300	$ 20,800	$ 22,400
Secured Floating Rate Notes | LIBOR
Debt Instrument [Line Items]
Variable rate of interest	3.75%	3.75%
Interest rate calculated on annual compounded basis (as a percent)				4.07%