Disposition of Business - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
	May 22, 2015	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pre-tax gain on disposal of business		$ 0	$ 0		$ 0	$ 508,810
Gain on disposal of business, after-tax						$ 395,000
Disposal Group, Not Discontinued Operations | eLong, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership sold	62.40%
Consideration of business sold	$ 671,000
Pre-tax gain on disposal of business				$ 509,000
Gain on disposal of business, after-tax				$ 395,000
Disposal Group, Not Discontinued Operations | eLong, Inc | Gain on sale of business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration of business sold, net of costs to sell	$ 666,000
Disposal Group, Not Discontinued Operations | eLong, Inc | Long-term investments and other assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Held in escrow		$ 67,000			$ 67,000