Overview and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Initial offering period		December 2011
Increase in revenue and income from continuing operations	$ 7.4	$ 8.2
Revenue and income from continuing operations		$ 9.9
Impact on reported earnings per share	$ 0.01	$ 0.02