Overview and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Initial offering period	December 2011
Increase in revenue and income from operations		$ 2.6
Revenue and income from operations		$ 1.3
Impact on reported earnings per share		$ 0.01
FASB issued ASU 2016-09
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Cumulative effect adjustment to retained earnings (a reduction in the accumulated deficit)	$ 48.2
Valuation allowance, deferred tax asset, increase (decrease), amount	97.3
Cumulative effect adjustment to retained earnings (an increase in the accumulated deficit)	$ 3.9