Basis of Presentation - Narrative (Detail) shares in Millions, $ in Millions	1 Months Ended		3 Months Ended		9 Months Ended
	Aug. 31, 2017 shares	Jun. 30, 2017 shares	Sep. 30, 2018 USD ($)	Sep. 30, 2017	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Mar. 31, 2017 shares	Oct. 01, 2016 Entity shares
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of entities resulted from spinoff of an entity | Entity									2
Effective income tax rate benefit			(42.60%)	(31.00%)	(72.00%)	(63.20%)
Cash payments for income taxes					$ 28.4	$ 34.1
Cash refunds for income taxes					14.0	20.7
Increase (decrease) in tax provisional estimates from changes in the Tax Act			$ (19.6)		(17.3)
Decrease in tax provisional estimates related to one-time transition tax			(19.0)
Decrease in tax provisional estimates related to change in federal income tax rate			(0.6)
Prepaid Expenses and Other Current Assets
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Income taxes receivable			$ 63.8		$ 63.8		$ 23.9
Donnelley Financial Solutions, Inc.
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Common shares distributed during spinoff | shares									26.2
Percentage of tax free distribution of common shares during spinoff									80.75%
Number of common shares held | shares									6.2
Non-cash debt-for-equity exchange, shares | shares	6.2	6.2
Realized gain (loss) on sale of retained shares						94.0
LSC Communications, Inc.
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Common shares distributed during spinoff | shares									26.2
Percentage of tax free distribution of common shares during spinoff									80.75%
Number of common shares held | shares								6.2	6.2
Realized gain (loss) on sale of retained shares						$ (51.6)