Fair Value Measurement - Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member]
¥ in Thousands, $ in Thousands |
Dec. 31, 2017
CNY (¥)
|
Dec. 31, 2017
USD ($)
|
Dec. 31, 2016
CNY (¥)
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Assets measured at fair value on recurring basis |
¥ 7,971,241
|
$ 1,225,158
|
¥ 4,764,458
|
| Restricted cash |
|
|
9,319
|
| Time Deposit [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Cash equivalents |
694,500
|
106,743
|
2,099,200
|
| Money Market Funds [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Cash equivalents |
34,105
|
5,242
|
225,848
|
| Short-term investments |
10,042
|
1,543
|
|
| Term Deposits [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Short-term investments |
842,912
|
129,554
|
1,804,208
|
| Adjustable-Rate Financial Products [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Short-term investments |
6,389,682
|
$ 982,076
|
625,883
|
| Fair Value Measurement Using Inputs Level 1 [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Assets measured at fair value on recurring basis |
34,105
|
|
225,848
|
| Restricted cash |
|
|
0
|
| Fair Value Measurement Using Inputs Level 1 [Member] | Time Deposit [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Cash equivalents |
0
|
|
0
|
| Fair Value Measurement Using Inputs Level 1 [Member] | Money Market Funds [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Cash equivalents |
34,105
|
|
225,848
|
| Short-term investments |
0
|
|
|
| Fair Value Measurement Using Inputs Level 1 [Member] | Term Deposits [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Short-term investments |
0
|
|
0
|
| Fair Value Measurement Using Inputs Level 1 [Member] | Adjustable-Rate Financial Products [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Short-term investments |
0
|
|
0
|
| Fair Value Measurement Using Inputs Level 2 [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Assets measured at fair value on recurring basis |
7,937,136
|
|
4,538,610
|
| Restricted cash |
|
|
9,319
|
| Fair Value Measurement Using Inputs Level 2 [Member] | Time Deposit [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Cash equivalents |
694,500
|
|
2,099,200
|
| Fair Value Measurement Using Inputs Level 2 [Member] | Money Market Funds [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Cash equivalents |
0
|
|
0
|
| Short-term investments |
10,042
|
|
|
| Fair Value Measurement Using Inputs Level 2 [Member] | Term Deposits [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Short-term investments |
842,912
|
|
1,804,208
|
| Fair Value Measurement Using Inputs Level 2 [Member] | Adjustable-Rate Financial Products [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Short-term investments |
6,389,682
|
|
625,883
|
| Fair Value Measurement Using Inputs Level 3 [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Assets measured at fair value on recurring basis |
0
|
|
0
|
| Restricted cash |
|
|
0
|
| Fair Value Measurement Using Inputs Level 3 [Member] | Time Deposit [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Cash equivalents |
0
|
|
0
|
| Fair Value Measurement Using Inputs Level 3 [Member] | Money Market Funds [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Cash equivalents |
0
|
|
0
|
| Short-term investments |
0
|
|
|
| Fair Value Measurement Using Inputs Level 3 [Member] | Term Deposits [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Short-term investments |
0
|
|
0
|
| Fair Value Measurement Using Inputs Level 3 [Member] | Adjustable-Rate Financial Products [Member] |
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
|
| Short-term investments |
¥ 0
|
|
¥ 0
|