Annual report pursuant to Section 13 and 15(d)

Income Taxes - Reconciliation of Summary of Activity of Company's Uncertain Tax Position (Detail)

v3.10.0.1
Income Taxes - Reconciliation of Summary of Activity of Company's Uncertain Tax Position (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits [Roll Forward]    
Beginning Balance $ 25.2 $ 25.2
Additions for tax positions related to prior years 0.0 0.0
Reductions for tax positions related to prior years (1.3) 0.0
Reductions due to tax settlements 0.0 0.0
Reductions due to tax statute of limitations 0.0 0.0
Ending Balance $ 23.9 $ 25.2