Acquisition of Global Workplace Solutions - Summary of Preliminary Estimate of Amortizable Intangible Assets Acquired (Detail) - Global Workplace Solutions (GWS) [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortizable intangibles acquired, Weighted Average Amortization Period	15 years
Total amortizable intangibles acquired, Amount Assigned At Acquisition Date	$ 736,250
Trademarks [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortizable intangibles acquired, Weighted Average Amortization Period	20 years
Total amortizable intangibles acquired, Amount Assigned At Acquisition Date	$ 450,500
Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortizable intangibles acquired, Weighted Average Amortization Period	10 years
Total amortizable intangibles acquired, Amount Assigned At Acquisition Date	$ 212,000
Non-compete agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortizable intangibles acquired, Weighted Average Amortization Period	3 years
Total amortizable intangibles acquired, Amount Assigned At Acquisition Date	$ 73,750