Litigation and Contingencies (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Average paid claim reduction due to curtailments (as a percent)	3.90%	5.80%
Probable loss contingency accrual	$ 23.5
Maximum exposure associated with other discussions and legal proceedings	$ 266.2