Debt (Summary of Debt) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Debt [Line Items]
Short-term debt	$ 8,687	$ 19,896
Long-term Debt, Total	703,337	711,298
Total debt	712,024	731,194
Current portion	15,648	13,126
Non-current portion	687,689	698,172
Delayed Draw Term Loans [Member]
Debt [Line Items]
Less: unamortized debt issue costs	(2,121)	(2,419)
Senior Unsecured Notes [Member]
Debt [Line Items]
Less: unamortized debt issue costs	$ (10,421)	(10,864)
4.342% Term Loan, Due October 2021 [Member]
Debt [Line Items]
Weighted average interest rate	4.342%
4.342% Term Loan, Due October 2021 [Member] \| Delayed Draw Term Loans [Member]
Debt [Line Items]
Long-term Debt	$ 163,189	161,891
Maturity date	Oct. 31, 2021
4.606% Term Loan, Due October 2021 [Member] \| Delayed Draw Term Loans [Member]
Debt [Line Items]
Long-term Debt	$ 52,690	62,690
Weighted average interest rate	4.606%
Maturity date	Oct. 31, 2021
5.375% Senior Unsecured Note, Due January 2025 [Member] \| Senior Unsecured Notes [Member]
Debt [Line Items]
Long-term Debt	$ 500,000	$ 500,000
Interest rate	5.375%
Maturity date	Jan. 31, 2025

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

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

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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Weighted average interest rate of debt outstanding.

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

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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