Early Termination Charges - Additional Information (Detail) $ in Thousands |
3 Months Ended | 6 Months Ended | 12 Months Ended | |
|---|---|---|---|---|
|
Jun. 30, 2017
USD ($)
Employee_Position
|
Mar. 31, 2017
USD ($)
|
Jun. 30, 2017
USD ($)
Employee_Position
|
Dec. 31, 2017
USD ($)
|
|
| Restructuring Cost and Reserve [Line Items] | ||||
| Early termination charges | $ 2,262 | $ 13,369 | ||
| Headcount Reduction Plan [Member] | ||||
| Restructuring Cost and Reserve [Line Items] | ||||
| Cash payments | $ 31,000 | |||
| Early termination charges | $ 2,262 | $ 11,107 | ||
| Number of employees elected to resign | Employee_Position | 352 | 352 | ||