Divestiture - Additional information (Detail) - Community Financial Services Products [Member] - Disposal Group, Not Discontinued Operations [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Mar. 03, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Amount of consideration related to disposal		$ 200.0
Net after-tax gain on the sale of assets	$ 93.4
Adjustment to Gain Loss on Sale of Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net after-tax gain on the sale of assets	$ 0.5