Stockholders' Equity - Scheduled Vesting for Outstanding Restricted Stock Units (Detail) (Restricted Stock Units) In Millions, unless otherwise specified	Mar. 31, 2014
Restricted Stock Units
Schedule of Vesting [Line Items]
Nine Months Ended December 31, 2014	4.5
Year Ended December 31, 2015	5.7
Year Ended December 31, 2016	3.4
Year Ended December 31, 2017	1.8
Year Ended December 31, 2018	0.2
Thereafter	0.1
Total	15.7