Other Obligations (Details 1) - USD ($)		3 Months Ended
	Feb. 21, 2014	Mar. 31, 2017	Mar. 31, 2016	Jan. 31, 2017	Dec. 31, 2016	Sep. 09, 2016	Jan. 23, 2015
Interest and Facility Fee Discussion
Outstanding letters of credit under the Credit Facility		$ 67,500,000
Write off debt issuance costs		702,000	$ 0
Credit Agreement and the A/R Securitization Program
Line of Credit Facility [Line Items]
Debt Instrument Term	5 years
Total Liquidity		454,600,000
Interest and Facility Fee Discussion
Unamortized debt issuance costs		7,100,000			$ 7,700,000
A/R Securitization Program
Line of Credit Facility [Line Items]
Maximum amount under senior secured revolving credit facility		21,600,000					$ 75,000,000
Borrowing capacity allowed		354,100,000		$ 70,000,000
Interest and Facility Fee Discussion
Outstanding borrowings		0
Senior Secured Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowing capacity allowed						$ 400,000,000
Interest and Facility Fee Discussion
Outstanding letters of credit under the Credit Facility		67,500,000				$ 250,000,000
Outstanding borrowings		$ 0