Discontinued Operations - Narrative (Detail) - USD ($) $ in Millions	1 Months Ended			12 Months Ended
	Aug. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 01, 2016
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Reduction of costs recognized within selling, general and administrative expenses				$ 7.7	$ 3.3
Net cash inflow from operating activities - discontinued operations				$ 126.1	17.8
Maximum
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Transition service agreement term				24 months
Donnelley Financial Solutions And L S C Communications
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
External sales					$ 150.4	$ 153.4
Donnelley Financial Solutions, Inc.
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Non-cash debt-for-equity exchange, shares	99,594	6,143,208
Extinguishment of indebtedness	$ 1.9	$ 111.6
Donnelley Financial Solutions, Inc. | Investment and Other (Expense ) Income, Net
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net realized gain	$ 1.6			$ 92.4
Donnelley Financial Solutions, Inc. | Spinoff | Available-for-Sale Equity Securities
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of common shares held				0			6,200,000
LSC Communications, Inc. | Investment and Other (Expense ) Income, Net
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Realized loss on sale of shares			$ 51.6
LSC Communications, Inc. | Spinoff
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of common shares sold			6,200,000
Net proceeds from sale of common shares			$ 121.4
LSC Communications, Inc. | Spinoff | Available-for-Sale Equity Securities
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of common shares held				0			6,200,000