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Revenue - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Disaggregation Of Revenue [Line Items]    
Increase in contract liabilies for customer deposits $ 18  
Revenue recognized included in deferred revenue   $ 8
Maximum [Member]    
Disaggregation Of Revenue [Line Items]    
Expected recognition period of revenue 1 year  
Amortization period of revenue recognized 1 year  
Accounting Standards Update 2014-09 [Member] | Receivables and Deferred Revenue [Member]    
Disaggregation Of Revenue [Line Items]    
Additional receivables and deferred revenue related to recognition of receivables with unconditional right to payment $ 5