Borrowings - Components of long-term debt (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total borrowings	$ 2,149,000	$ 2,176,500
Less: Unamortized debt issuance costs	(17,628)	(17,675)
Total long-term debt	2,131,372	2,158,825
Current borrowings	(50,000)	(86,625)
Long-term borrowings	2,081,372	2,072,200
Revolving Credit Facility
Debt Instrument [Line Items]
Senior Credit Facility:	$ 276,000	293,000
Line of credit facility interest rate	3.90%
Term Loan
Debt Instrument [Line Items]
Senior Credit Facility:	$ 673,000	683,500
Line of credit facility interest rate	3.90%
Senior Notes \| 5.25% Senior Notes due 2024
Debt Instrument [Line Items]
Senior Notes	$ 250,000	250,000
Debt instrument, stated interest rate	5.25%
Senior Notes \| 4.875% Senior Notes due 2026
Debt Instrument [Line Items]
Senior Notes	$ 400,000	400,000
Debt instrument, stated interest rate	4.875%
Senior Notes \| 4.625% Senior Notes due 2027
Debt Instrument [Line Items]
Senior Notes	$ 500,000	500,000
Debt instrument, stated interest rate	4.625%
Securitization program
Debt Instrument [Line Items]
Securitization program, at a rate of 3.15% at June 30, 2019	$ 50,000	$ 50,000
Debt instrument, stated interest rate	3.15%

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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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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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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The effective interest rate during the reporting period.

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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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Amount of borrowings classified as other, maturing within one year or the normal operating cycle, if longer.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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