Discontinued Operations and Divestitures - Additional Information (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($) Office	Mar. 31, 2017 Office	Dec. 31, 2017 USD ($)	Dec. 31, 2015 Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of business divestiture | Office	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
Benefits and Insurance Segment [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 | $	$ 700		$ 22