Revenue Recognition and Accounts Receivable - Additional Information (Detail) - USD ($) |
3 Months Ended | 12 Months Ended | |
|---|---|---|---|
Mar. 31, 2018 |
Dec. 31, 2017 |
Jan. 01, 2018 |
|
| Other Contract Assets [Member] | |||
| Revenue Recognition And Accounts Receivable [Line Items] | |||
| Other contract assets impairment | $ 0 | $ 0 | |
| Other Noncurrent Assets [Member] | |||
| Revenue Recognition And Accounts Receivable [Line Items] | |||
| Other contract assets | $ 800,000 | $ 1,000,000 | |
| Topic 606 [Member] | |||
| Revenue Recognition And Accounts Receivable [Line Items] | |||
| Net increase to opening retained earnings due to cumulative impact of adoption | $ 4,800,000 |