Fair Value Measurement-Estimated Fair Values (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted investments, held to maturity, amortized cost	[1]	$ 22,859	$ 22,717
Restricted Investments, Estimated Fair Value	[1]	22,843	22,688
2015 Agreement, New Term Loan A, due July 2020, Carrying Amount		476,878	501,805
Accounts receivable securitization, due January 2019, Carrying Amount		304,374	279,285
Revolving line of credit, Carrying Amount	[2],[3]	10,000	130,000
Deferred loan costs		2,957	3,222
2015 Agreement, New Term Loan A [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
2015 Agreement, New Term Loan A, due July 2020, Carrying Amount	[2],[4]	470,506	492,912
2015 Agreement, New Term Loan A, due July 2020, Fair Value	[4]	471,750	494,250
Deferred loan costs		1,244	1,338
2015 RSA [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts receivable securitization, due January 2019, Carrying Amount	[5]	304,374	279,285
Accounts receivable securitization, due January 2019, Fair Value	[5]	305,000	280,000
Deferred loan costs		600	700
2015 Agreement, New Revolver [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revolving line of credit, Carrying Amount		10,000	130,000
Revolving line of credit, Fair Value		$ 10,000	$ 130,000

[1] Restricted investments are included in "Restricted investments, held to maturity, amortized cost."

[2] Refer to Note 14 for information regarding the fair value of long-term debt.

[3] The Company also had outstanding letters of credit under the Revolver, primarily related to workers' compensation and self-insurance liabilities of $95.2 million at March 31, 2017 and $97.0 million at December 31, 2016.

[4] Carrying value is net of $1.2 million and $1.3 million DLCs as of March 31, 2017 and December 31, 2016, respectively. The Term Loan A is included in "Long-term debt, less current portion," as the Company has voluntarily prepaid all minimum quarterly principal payments through final maturity.

[5] Carrying value is net of $0.6 million and $0.7 million DLCs as of March 31, 2017 and December 31, 2016, respectively.