Debt - 4.000% Senior Unsecured Notes Due 2022 - Additional Information (Detail) - 4.000% Senior Unsecured Notes Due 2022 [Member] - EUR (€)		12 Months Ended
	Aug. 19, 2015	Dec. 31, 2018
Debt Instrument [Line Items]
Senior unsecured notes face amount	€ 500,000,000
Senior unsecured notes, interest rate	4.00%
Senior unsecured notes, payable term		Interest on the notes is payable annually on August 19 of each year.
Senior unsecured notes, maturity date	Aug. 19, 2022
Senior unsecured notes, redemption period	90 days
Senior notes, repurchased price percentage on principal amount plus accrued and unpaid interest	101.00%
Senior unsecured notes, redemption description		Notes are redeemed prior to 90 days before maturity, the redemption price will be 100% of their principal amount, plus a make-whole premium, plus accrued and unpaid interest to, but excluding, the applicable redemption date. Within the period beginning on or after 90 days before maturity, the notes may be redeemed, in whole or in part, at a redemption price equal to 100% of their principal amount, plus accrued and unpaid interest to, but excluding, the applicable redemption date. The 4.000% Senior Unsecured Notes due 2022 are fully and unconditionally guaranteed on an unsecured basis by us. In the event of a change of control, each holder of the notes may require us to repurchase some or all of our notes at a repurchase price equal to 101% of the aggregate principal amount of the notes plus accrued and unpaid interest to the date of the purchase.
Redeemed Prior to 90 Days [Member]
Debt Instrument [Line Items]
Senior unsecured notes, redemption price percentage	100.00%
Redeemed Beginning on or After 90 Days [Member]
Debt Instrument [Line Items]
Senior unsecured notes, redemption price percentage	100.00%