Notes Payable - Additional Information (Details)	1 Months Ended
Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Refinancing transaction amount	$ 425,000,000	$ 425,000,000
Maximum total leverage ratio	3.0
Maximum total leverage ratio in event of an acquisition	4.00
Minimum
Debt Instrument [Line Items]
Maximum total leverage ratio	3.5
Maximum
Debt Instrument [Line Items]
Maximum total leverage ratio	3.5
2018 Credit Agreement
Debt Instrument [Line Items]
Debt fees and acquisition costs	$ 4,000,000
Capitalized debt fees and acquisition costs	3,000,000
Debt fees and acquisition costs expensed in period	2,000,000
Revolving Credit Facility \| 2018 Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity under credit facility	75,000,000
Revolving Credit Facility \| 2018 Revolver
Debt Instrument [Line Items]
Maximum borrowing capacity under credit facility	250,000,000
Letter of Credit \| 2018 Credit Agreement
Debt Instrument [Line Items]
Undrawn letter of credit	16,000,000
Notes Payable \| 2018 Term Loan A
Debt Instrument [Line Items]
Face amount of term loan facility	425,000,000
Refinancing transaction amount	425,000,000	$ 0
Amount rolled over into new borrowing	211,000,000
Notes Payable \| 2014 Term Loans
Debt Instrument [Line Items]
Debt refinanced and repaid	415,000,000
Refinancing transaction amount	415,000,000
Extinguishment of debt	$ 204,000,000

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Debt Instrument, Covenant, Interest Coverage Ratio, Maximum Allowable Ratio In Event Of Business Acquisition

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Face (par) amount of debt instrument at time of issuance.

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Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Gross amount of debt extinguished.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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