Derivative Financial Instruments - Summary of Outstanding Interest Rate Derivatives Designated as Cash Flow Hedges of Interest Rate Risk (Detail) - 9 months ended Sep. 30, 2015 - Cash Flow Hedges [Member] - Designated as Hedging Instrument [Member] - Interest Rate Caps [Member] € in Thousands, £ in Thousands, CAD in Thousands, $ in Thousands	USD ($) DerivativeInstrument	GBP (£) DerivativeInstrument	CAD DerivativeInstrument	EUR (€) DerivativeInstrument
USD [Member] | USD LIBOR [Member]
Derivative [Line Items]
Number of Instruments	26	26	26	26
Notional Amount | $	$ 1,097,632
Strike	2.00%	2.00%	2.00%	2.00%
Wtd. Avg. Maturity (Years)	1 year 7 months 6 days
CAD [Member] | CDOR [Member]
Derivative [Line Items]
Number of Instruments	11	11	11	11
Notional Amount | CAD			CAD 550,589
Strike	2.00%	2.00%	2.00%	2.00%
Wtd. Avg. Maturity (Years)	1 year 6 months
EUR [Member] | EURIBOR [Member]
Derivative [Line Items]
Number of Instruments	1	1	1	1
Notional Amount | €				€ 152,710
Strike	2.00%	2.00%	2.00%	2.00%
Wtd. Avg. Maturity (Years)	1 year 3 months 18 days
GBP [Member] | GBP LIBOR [Member]
Derivative [Line Items]
Number of Instruments	1	1	1	1
Notional Amount | £		£ 15,142
Strike	2.00%	2.00%	2.00%	2.00%
Wtd. Avg. Maturity (Years)	1 year 7 months 6 days