Long-term Debt - Schedule of Long-term Debt (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Debt Instrument [Line Items]
Total long-term debt	$ 301,500,000		$ 301,500,000		$ 382,100,000
Amortization of debt issuance costs			400,000	$ 400,000
Revolving credit facility
Debt Instrument [Line Items]
Unamortized debt issuance costs	1,300,000		1,300,000		1,700,000
Revolving credit facility, expansion feature	200,000,000		200,000,000
Average borrowings	354,300,000	$ 235,200,000	345,300,000	256,300,000
Unused Credit Facility and letter of credit participation fees	300,000	300,000	600,000	700,000
Amortization of debt issuance costs	$ 200,000	$ 200,000	$ 400,000	$ 400,000
Weighted-average interest rate	1.40%	3.70%	2.10%	3.70%
Revolving credit facility
Debt Instrument [Line Items]
Total long-term debt	$ 225,000,000.0		$ 225,000,000.0		324,800,000
Outstanding letters of credit	19,400,000		19,400,000		16,700,000
Amounts available to borrow	494,400,000		494,400,000		341,700,000
Obligations under capital leases
Debt Instrument [Line Items]
Total long-term debt	76,500,000		76,500,000		$ 57,300,000
Minimum | Revolving credit facility
Debt Instrument [Line Items]
Average borrowings	225,000,000.0	$ 141,700,000	151,500,000	$ 141,700,000
Maximum | Revolving credit facility
Debt Instrument [Line Items]
Average borrowings	$ 451,000,000.0	$ 330,600,000	$ 499,300,000	$ 390,000,000.0