Summary of Components of Interest as Presented in Consolidated Statements of Operations (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Debt Instrument [Line Items]
Tax benefit related to settlement of state and local income tax audits			$ 2.0
Reversal of accrued interest expense related to Legacy Tax Matter			2.0
Income	$ 1.7	$ 1.2	$ 3.3	$ 2.4