Required periodic principal payments per loan year as a percentage of total principal.

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Maximum aggregate commitments with respect to an increase in the Revolving Credit Facility, additional term loans, or a combination thereof that may be requested under the Credit Agreement.

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Maximum percent of shares of certain foreign subsidiaries

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Amount of amortization expense attributable to debt issuance costs.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Description of the frequency of periodic payments (monthly, quarterly, annual).

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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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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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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Amount of cash inflow from issuance of long-term debt classified as other.

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Amount of cash outflow for the payment of debt classified as other, maturing after one year or the operating cycle, if longer.

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Long-Term Debt - Credit Agreement (Details) - USD ($)		1 Months Ended			12 Months Ended
Long-Term Debt - Credit Agreement (Details) - USD ($)	Jun. 30, 2017	Mar. 31, 2018	Jun. 30, 2017	Feb. 29, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Principal amount					$ 479,161,000
Proceeds from term loan					0	$ 100,000,000	$ 0
Repayment of term loan					63,807,000	194,758,000	62,742,000
Loss on extinguishment of long-term debt					(1,183,000)	(397,000)	(3,540,000)
Amortization of debt issuance costs					3,592,000	6,154,000	$ 7,733,000
Collateral Pledged
Debt Instrument [Line Items]
Maximum percent of shares of foreign subsidiaries	66.00%
Term Loan Maturing June 2020
Debt Instrument [Line Items]
Principal amount	$ 100,000,000		$ 100,000,000		$ 33,693,000	$ 97,500,000
Proceeds from term loan	$ 100,000,000
Repayment of term loan		$ 61,000,000
Interest rate (as a percent)					6.77%
Frequency of periodic payment	quarterly
Loss on extinguishment of long-term debt		$ (900,000)
Term Loan Maturing June 2020 \| First Loan Year
Debt Instrument [Line Items]
Periodic principal payment (as a percent)	5.00%
Term Loan Maturing June 2020 \| Second Loan Year
Debt Instrument [Line Items]
Periodic principal payment (as a percent)	10.00%
Term Loan Maturing June 2020 \| Third Loan Year
Debt Instrument [Line Items]
Periodic principal payment (as a percent)	15.00%
Term Loan Maturing June 2020 \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.25%
Term Loan Maturing June 2020 \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	4.25%
Revolving Credit Facility Maturing June 2020
Debt Instrument [Line Items]
Borrowing capacity	$ 150,000,000		150,000,000
Additional commitments (up to)	$ 100,000,000		100,000,000
Available borrowing capacity					$ 147,400,000
Letters of credit issued					$ 2,600,000
Commitment fee percentage	0.50%
Amortization of debt issuance costs			1,600,000
Revolving Credit Facility Maturing June 2020 \| Base Rate \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.75%
Revolving Credit Facility Maturing June 2020 \| Base Rate \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.25%
Revolving Credit Facility Maturing June 2020 \| LIBOR \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.75%
Revolving Credit Facility Maturing June 2020 \| LIBOR \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	4.25%
Term Loan and Revolving Loans
Debt Instrument [Line Items]
Maturity date	Jun. 30, 2020
Letter of Credit
Debt Instrument [Line Items]
Borrowing capacity	$ 25,000,000		25,000,000
Former Term Loan
Debt Instrument [Line Items]
Repayment of term loan	$ 180,000,000
Loss on extinguishment of long-term debt			$ (400,000)
Former Revolving Credit Facility
Debt Instrument [Line Items]
Amortization of debt issuance costs				$ 2,500,000