Condensed Consolidating Guarantor Financial Information - Condensed Cash Flow Statement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities:
Net cash provided by (used in) operating activities	$ 924	$ 1,365	$ 1,446
Investing Activities:
Capital expenditures for property and equipment	(58)	(317)	(310)
Acquisitions, net of cash acquired	0	0	(1,402)
Issuance of intercompany receivables		0
Payments received on intercompany receivables		0
Proceeds from asset dispositions	0	11	2,205
Contract acquisition costs	(75)	(55)	(37)
Capitalized software costs	(75)	(81)	(62)
Other	(14)	(36)	20
Net cash provided by (used in) investing activities	(222)	(478)	414
Financing Activities:
Borrowings	1,824	4,715	48
Repayment of debt	(1,860)	(4,359)	(1,624)
Debt issuance costs and redemption premium	(69)	(76)	0
Intercompany borrowings		0
Repayments of intercompany borrowings	0	0
Intercompany transfers	0	0	0
Dividends paid	(195)	(277)	(138)
Intercompany dividends	0	0	0
Cash transferred in spin-offs of Park and HGV	501	0	0
Repurchases of common stock	(891)	0	0
Distributions to noncontrolling interests	(1)	(32)	(8)
Tax withholdings on share-based compensation	(31)	(15)	(31)
Net cash provided by (used in) financing activities	(1,724)	(44)	(1,753)
Effect of exchange rate changes on cash, restricted cash and cash equivalents	8	(15)	(19)
Net increase (decrease) in cash, restricted cash and cash equivalents	(1,014)	828	88
Cash, restricted cash and cash equivalents from continuing operations, beginning of period	1,183	633	628
Cash, restricted cash and cash equivalents from discontinued operations, beginning of period	501	223	140
Cash, restricted cash and cash equivalents, beginning of period	1,684	856	768
Cash, restricted cash and cash equivalents from continuing operations, end of period	670	1,183	633
Cash, restricted cash and cash equivalents from discontinued operations, end of period	0	501	223
Cash, restricted cash and cash equivalents, end of period	670	1,684	856
Eliminations [member]
Operating Activities:
Net cash provided by (used in) operating activities	(170)	(605)	(436)
Investing Activities:
Capital expenditures for property and equipment	0	0	0
Acquisitions, net of cash acquired			0
Issuance of intercompany receivables		234
Payments received on intercompany receivables		(192)
Proceeds from asset dispositions		0	0
Contract acquisition costs	0	0	0
Capitalized software costs	0	0	0
Other	(3)	0	0
Net cash provided by (used in) investing activities	(3)	42	0
Financing Activities:
Borrowings	0	0	0
Repayment of debt	0	0	0
Debt issuance costs and redemption premium	0	0
Intercompany borrowings		(234)
Repayments of intercompany borrowings	3	192
Intercompany transfers	0	0	0
Dividends paid	0	0	0
Intercompany dividends	170	605	436
Cash transferred in spin-offs of Park and HGV	0
Repurchases of common stock	0
Distributions to noncontrolling interests	0	0	0
Tax withholdings on share-based compensation	0	0	0
Net cash provided by (used in) financing activities	173	563	436
Effect of exchange rate changes on cash, restricted cash and cash equivalents	0	0	0
Net increase (decrease) in cash, restricted cash and cash equivalents	0	0	0
Cash, restricted cash and cash equivalents from continuing operations, beginning of period	0	0	0
Cash, restricted cash and cash equivalents from discontinued operations, beginning of period	0	0	0
Cash, restricted cash and cash equivalents, beginning of period	0	0	0
Cash, restricted cash and cash equivalents from continuing operations, end of period		0	0
Cash, restricted cash and cash equivalents from discontinued operations, end of period		0	0
Cash, restricted cash and cash equivalents, end of period	0	0	0
Parent [member]
Operating Activities:
Net cash provided by (used in) operating activities	0	0	0
Investing Activities:
Capital expenditures for property and equipment	0	0	0
Acquisitions, net of cash acquired			0
Issuance of intercompany receivables		0
Payments received on intercompany receivables		0
Proceeds from asset dispositions		0	0
Contract acquisition costs	0	0	0
Capitalized software costs	0	0	0
Other	0	0	0
Net cash provided by (used in) investing activities	0	0	0
Financing Activities:
Borrowings	0	0	0
Repayment of debt	0	0	0
Debt issuance costs and redemption premium	0	0
Intercompany borrowings		0
Repayments of intercompany borrowings	0	0
Intercompany transfers	1,086	277	138
Dividends paid	(195)	(277)	(138)
Intercompany dividends	0	0	0
Cash transferred in spin-offs of Park and HGV	0
Repurchases of common stock	(891)
Distributions to noncontrolling interests	0	0	0
Tax withholdings on share-based compensation	0	0	0
Net cash provided by (used in) financing activities	0	0	0
Effect of exchange rate changes on cash, restricted cash and cash equivalents	0	0	0
Net increase (decrease) in cash, restricted cash and cash equivalents	0	0	0
Cash, restricted cash and cash equivalents from continuing operations, beginning of period	0	0	0
Cash, restricted cash and cash equivalents from discontinued operations, beginning of period	0	0	0
Cash, restricted cash and cash equivalents, beginning of period	0	0	0
Cash, restricted cash and cash equivalents from continuing operations, end of period		0	0
Cash, restricted cash and cash equivalents from discontinued operations, end of period		0	0
Cash, restricted cash and cash equivalents, end of period	0	0	0
Guarantor Subsidiaries [member]
Operating Activities:
Net cash provided by (used in) operating activities	988	912	975
Investing Activities:
Capital expenditures for property and equipment	(12)	(9)	(11)
Acquisitions, net of cash acquired			0
Issuance of intercompany receivables		(192)
Payments received on intercompany receivables		192
Proceeds from asset dispositions		0	0
Contract acquisition costs	(38)	(46)	(23)
Capitalized software costs	(75)	(73)	(57)
Other	(1)	(35)	13
Net cash provided by (used in) investing activities	(126)	(163)	(78)
Financing Activities:
Borrowings	0	0	0
Repayment of debt	0	0	0
Debt issuance costs and redemption premium	0	0
Intercompany borrowings		42
Repayments of intercompany borrowings	0	0
Intercompany transfers	(865)	(854)	(693)
Dividends paid	0	0	0
Intercompany dividends	0	0	(184)
Cash transferred in spin-offs of Park and HGV	0
Repurchases of common stock	0
Distributions to noncontrolling interests	0	0	0
Tax withholdings on share-based compensation	0	(15)	(31)
Net cash provided by (used in) financing activities	(865)	(827)	(908)
Effect of exchange rate changes on cash, restricted cash and cash equivalents	0	0	0
Net increase (decrease) in cash, restricted cash and cash equivalents	(3)	(78)	(11)
Cash, restricted cash and cash equivalents from continuing operations, beginning of period	31	109	119
Cash, restricted cash and cash equivalents from discontinued operations, beginning of period	0	0	1
Cash, restricted cash and cash equivalents, beginning of period	31	109	120
Cash, restricted cash and cash equivalents from continuing operations, end of period		31	109
Cash, restricted cash and cash equivalents from discontinued operations, end of period		0	0
Cash, restricted cash and cash equivalents, end of period	28	31	109
Non-Guarantor Subsidiaries [member]
Operating Activities:
Net cash provided by (used in) operating activities	322	1,095	723
Investing Activities:
Capital expenditures for property and equipment	(34)	(308)	(299)
Acquisitions, net of cash acquired			(1,402)
Issuance of intercompany receivables		(42)
Payments received on intercompany receivables		0
Proceeds from asset dispositions		11	2,205
Contract acquisition costs	(37)	(9)	(14)
Capitalized software costs	0	(8)	(5)
Other	3	5	7
Net cash provided by (used in) investing activities	(68)	(351)	492
Financing Activities:
Borrowings	2	3,715	48
Repayment of debt	(8)	(4,093)	(849)
Debt issuance costs and redemption premium	0	(39)
Intercompany borrowings		192
Repayments of intercompany borrowings	0	(192)
Intercompany transfers	(568)	1,141	(36)
Dividends paid	0	0	0
Intercompany dividends	(170)	(605)	(252)
Cash transferred in spin-offs of Park and HGV	501
Repurchases of common stock	0
Distributions to noncontrolling interests	(1)	(32)	(8)
Tax withholdings on share-based compensation	0	0	0
Net cash provided by (used in) financing activities	(1,246)	87	(1,097)
Effect of exchange rate changes on cash, restricted cash and cash equivalents	8	(15)	(19)
Net increase (decrease) in cash, restricted cash and cash equivalents	(984)	816	99
Cash, restricted cash and cash equivalents from continuing operations, beginning of period	1,062	524	509
Cash, restricted cash and cash equivalents from discontinued operations, beginning of period	501	223	139
Cash, restricted cash and cash equivalents, beginning of period	1,563	747	648
Cash, restricted cash and cash equivalents from continuing operations, end of period		1,062	524
Cash, restricted cash and cash equivalents from discontinued operations, end of period		501	223
Cash, restricted cash and cash equivalents, end of period	579	1,563	747
HWF Issuers [member]
Operating Activities:
Net cash provided by (used in) operating activities	(113)	(37)	184
Investing Activities:
Capital expenditures for property and equipment	0	0	0
Acquisitions, net of cash acquired			0
Issuance of intercompany receivables		0
Payments received on intercompany receivables		0
Proceeds from asset dispositions		0	0
Contract acquisition costs	0	0	0
Capitalized software costs	0	0	0
Other	(13)	(6)	0
Net cash provided by (used in) investing activities	(13)	(6)	0
Financing Activities:
Borrowings	1,822	0	0
Repayment of debt	(1,852)	(266)	(775)
Debt issuance costs and redemption premium	(69)	(17)
Intercompany borrowings		0
Repayments of intercompany borrowings	0	0
Intercompany transfers	225	326	591
Dividends paid	0	0	0
Intercompany dividends	0	0	0
Cash transferred in spin-offs of Park and HGV	0
Repurchases of common stock	0
Distributions to noncontrolling interests	0	0	0
Tax withholdings on share-based compensation	0	0	0
Net cash provided by (used in) financing activities	126	43	(184)
Effect of exchange rate changes on cash, restricted cash and cash equivalents	0	0	0
Net increase (decrease) in cash, restricted cash and cash equivalents	0	0	0
Cash, restricted cash and cash equivalents from continuing operations, beginning of period	0	0	0
Cash, restricted cash and cash equivalents from discontinued operations, beginning of period	0	0	0
Cash, restricted cash and cash equivalents, beginning of period	0	0	0
Cash, restricted cash and cash equivalents from continuing operations, end of period		0	0
Cash, restricted cash and cash equivalents from discontinued operations, end of period		0	0
Cash, restricted cash and cash equivalents, end of period	0	0	0
HOC [member]
Operating Activities:
Net cash provided by (used in) operating activities	(103)	0
Investing Activities:
Capital expenditures for property and equipment	(12)	0
Issuance of intercompany receivables		0
Payments received on intercompany receivables		0
Proceeds from asset dispositions		0
Contract acquisition costs	0	0
Capitalized software costs	0	0
Other	0	0
Net cash provided by (used in) investing activities	(12)	0
Financing Activities:
Borrowings	0	1,000
Repayment of debt	0	0
Debt issuance costs and redemption premium	0	(20)
Intercompany borrowings		0
Repayments of intercompany borrowings	(3)	0
Intercompany transfers	122	(890)
Dividends paid	0	0
Intercompany dividends	0	0
Cash transferred in spin-offs of Park and HGV	0
Repurchases of common stock	0
Distributions to noncontrolling interests	0	0
Tax withholdings on share-based compensation	(31)	0
Net cash provided by (used in) financing activities	88	90
Effect of exchange rate changes on cash, restricted cash and cash equivalents	0	0
Net increase (decrease) in cash, restricted cash and cash equivalents	(27)	90
Cash, restricted cash and cash equivalents from continuing operations, beginning of period	90	0
Cash, restricted cash and cash equivalents from discontinued operations, beginning of period	0	0
Cash, restricted cash and cash equivalents, beginning of period	90	0
Cash, restricted cash and cash equivalents from continuing operations, end of period		90	0
Cash, restricted cash and cash equivalents from discontinued operations, end of period		0	0
Cash, restricted cash and cash equivalents, end of period	$ 63	$ 90	$ 0