Senior Notes and Other Long-Term Debt - Components of Long-Term Debt (Parenthetical) (Detail) - Ex-Im Credit Facility [Member] - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016
Other Long-Term Debt
Exposure fees accrued as of balance sheet date expected to be financed under the Ex-Im Credit Facility	$ 29.5	$ 21.0
Unamortized discount and debt issuance costs on Ex-Im Credit Facility related to the exposure fees expected to be financed under the Ex-Im Credit Facility	$ 23.0	$ 18.7