Financial Instruments and Fair Value Measurements - Summary of Gains (Losses) From Change in Fair Value of Derivative Instruments Included in Other Comprehensive Income (Loss) (Parenthetical) (Detail) $ in Thousands, € in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 EUR (€)	Dec. 31, 2014 USD ($)	Dec. 31, 2014 EUR (€)
Derivative Instruments Gain Loss [Line Items]
Amount received from (paid for) on settlement of net investment hedges		$ 5,900	$ 121,500	$ (5,500)
Interest expense reclassified	$ 81,035	69,086	218,698	234,793
Debt	11,934,355		11,934,355				$ 9,380,199
Amount of gain (loss) included in AOCI	(148,570)	(130,763)	(197,912)	(72,022)
Foreign Currency Forward Contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of gain (loss) included in AOCI	0	$ 0	10,000	$ 0
Foreign Currency Forward Contracts [Member] | Designated As Hedging Instrument [Member]
Derivative Instruments Gain Loss [Line Items]
Debt	$ 3,600,000		$ 3,600,000			€ 3,200.0	3,000,000	€ 2,500.0
Foreign Currency Forward Contracts [Member] | Nondesignated [Member]
Derivative Instruments Gain Loss [Line Items]
Debt							$ 118,500	€ 97.6
Scenario Forecast | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Derivative Instruments Gain Loss [Line Items]
Interest expense reclassified					$ 7,600