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Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2019 | Mar. 31, 2018
Equity [Abstract] |  |
Balance at beginning of period, Pension and Postretirement Benefit Plans | $ 84,207 | $ 79,938
Tax effect of other comprehensive earnings, Pension and Postretirement Benefit Plans | (868) | (658)
Balance at end of period, Pension and Postretirement Benefit Plans | 83,339 | 79,280
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap |  | 178
Tax effect of other comprehensive earnings, Unamortized Value of Terminated Forward Starting Interest Rate Swap |  | (137)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap |  | 41
Balance at beginning of period, Net Noncurrent Deferred Tax Assets | 84,207 | 80,116
Tax effect of other comprehensive earnings, Net Noncurrent Deferred Tax Assets | (868) | (795)
Balance at end of period, Net Noncurrent Deferred Tax Assets | $ 83,339 | $ 79,321

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