Commitments and Contingencies - Legal Matters - Additional Information (Detail)	6 Months Ended	198 Months Ended
	Jun. 30, 2018 USD ($) Case	Jun. 30, 2018 USD ($) Case	Dec. 31, 2017 Case
Commitments And Contingencies Disclosure [Abstract]
Cumulative settlement payments for cases involving asbestos-related claims | $		$ 2,900,000
Cumulative settlement payments made for cases involving asbestos-related claims with all legal fees other than corporate counsel expenses | $		2,800,000
Average cost per settled claim excluding legal fees | $	$ 37,000	$ 37,000
Number of claims pending	203	203	218
Number of new cases filed	53
Number of cases dismissed	29
Number of cases settled	39
Assessment regarding Loss contingency impact Description	We are not aware of pending claims or assessments, other than as described above, which may have a material adverse impact on our liquidity, financial position, results of operations, or cash flows.