Acquisitions and Dispositions - Acquisitions (Detail) ZAR in Millions, CAD in Millions, $ in Millions	3 Months Ended
	Jun. 30, 2015 CAD hotel hotel_and_resort room	Jun. 30, 2015 USD ($) hotel hotel_and_resort room	Jun. 30, 2014 USD ($)	Jun. 30, 2014 ZAR	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Goodwill | $					$ 962	$ 894
Delta Hotels and Resorts
Business Acquisition [Line Items]
Cash paid for acquisition	CAD 170	$ 134
Working capital acquired	2	2
Purchase price of acquisition	172	136
Intangible assets including goodwill	158				125
Deferred contract acquisition costs	22	$ 17
Brand intangible	115				91
Goodwill	22				17
Tangible assets consisting of property and equipment and other current assets	CAD 14				$ 11
Number of open hotels and resorts acquired	37	37
Number of rooms acquired | room	9,595	9,595
Number of managed hotels and resorts acquired	27	27
Number of managed hotels and resorts acquired, 30 year management agreement	13	13
Number of franchised hotels and resorts acquired	10	10
Number of hotels and resorts under development acquired	5	5
Number of hotels and resorts under development acquired, 30 year management agreement | hotel	1	1
Protea Hospitality Holdings
Business Acquisition [Line Items]
Cash paid for acquisition			$ 195	ZAR 2,059
Increase of goodwill | $		$ 52
Brand | Protea Hospitality Holdings
Business Acquisition [Line Items]
Decrease of intangibles-lived brand | $		12
Contract Assets | Protea Hospitality Holdings
Business Acquisition [Line Items]
Decrease of intangibles-lived brand | $		$ 40