Commitments and Contingencies - Summary of Average Resolutions Per Claim Excluding Legal Costs (Details) - $ / Claim	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Malignant claims	55,300	56,000	44,000	44,000	53,500
Nonmalignant claims	4,700	2,800	4,485	100	120