Financial Instruments - Derivatives and Hedging (Details) € in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 EUR (€)	Jan. 31, 2019 USD ($)	Jan. 31, 2019 EUR (€)	Dec. 31, 2018 USD ($)
Derivative Instruments, Gain (Loss)
Gain (loss) to be reclassified during next 12 months	$ 5,100,000
Domestic Line of Credit | First Lien Credit Facility - U.S. Dollar Term Loans, due 2026
Derivative Instruments, Gain (Loss)
Debt face amount			$ 750,000,000
Foreign Exchange Forward
Derivative Instruments, Gain (Loss)
Derivative notional amount	$ 39,500,000				$ 28,900,000
Derivative remaining maturity	1 year
Interest rate swaps
Derivative Instruments, Gain (Loss)
Proceeds from settlement of derivatives	$ 8,200,000
Amount reclassified from AOCI to income during the period	7,100,000
Interest rate swaps | Notes Payable to Banks | USD Notes
Derivative Instruments, Gain (Loss)
Derivative notional amount	$ 1,120,000,000
Interest rate swap rate (as a percent)	1.96%	1.96%
Interest rate swaps | Notes Payable to Banks | Euro Notes
Derivative Instruments, Gain (Loss)
Derivative notional amount | €		€ 276
Interest rate swap rate (as a percent)	1.20%	1.20%
Interest rate swaps | Medium-term Notes | Euro Notes
Derivative Instruments, Gain (Loss)
Derivative notional amount | €				€ 662
Interest rate swap rate (as a percent)			2.40%	2.40%
Not Designated as Hedging Instrument | Foreign Exchange Forward
Derivative Instruments, Gain (Loss)
Derivative notional amount	$ 148,800,000				$ 102,000,000
Derivative remaining maturity	1 year