Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Income Taxes - Reconciliation of Unrecognized Tax Benefits and Interest and Penalties (Detail)

v3.7.0.1
Income Taxes - Reconciliation of Unrecognized Tax Benefits and Interest and Penalties (Detail) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Mar. 31, 2015
Income Tax Disclosure [Abstract]      
Unrecognized tax benefits, Beginning balance $ 0.7 $ 4.9 $ 0.5
Unrecognized tax benefits, Additions for tax positions of the current year 0.1 0.2 4.2
Unrecognized tax benefits, Additions for tax positions of prior year     0.2
Unrecognized tax benefits, Reductions in tax positions of prior year (0.1) (4.1)  
Unrecognized tax benefits, Settlements paid during the current period   (0.3)  
Unrecognized tax benefits, Ending Balance $ 0.7 0.7 4.9
Interest and Penalties, Beginning balance   0.3  
Interest and Penalties, Additions for tax positions of the current year     0.1
Interest and Penalties, Additions for tax positions of prior year     0.2
Interest and Penalties, Reductions in tax positions of prior year   (0.3)  
Interest and Penalties, Settlements paid during the current period   $ 0.0  
Interest and Penalties, Ending Balance     $ 0.3