Retirement Plans - Additional Information (Detail) |
12 Months Ended |
---|---|
Dec. 31, 2017
Plans
| |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |
Number of retirement plans | 2 |
Maximum [Member] | |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |
Maximum legal limit of employer contribution to plan | 3.00% |