Interim Financial Data - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended
	Sep. 30, 2018	Apr. 01, 2018
Accounting Standards Update 2014-09 [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance Policy Term	3 months
Accounting Standards Update 2014-09 [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance Policy Term	120 months
Accounting Standards Update 2016-01 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect of adoption of the guidance, reduction in retained earnings		$ 12