Discontinued Operations and Divestitures - Additional Information (Detail) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($) Business	Sep. 30, 2018 USD ($) Business	Dec. 31, 2015 Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of businesses sold | Business	0	0
Financial Services [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of businesses sold | Business			2
Financial Services Practice Group [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain from the sale of its individual wealth management business | $	$ 0.4
Benefits and Insurance Services Practice Group [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain from the sale of its individual wealth management business | $		$ 0.7