Acquisitions - Purchase Price Allocation of ReD (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 913,261	$ 909,691	$ 781,163
Retail Decisions [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	795
Receivables	10,106
Other current assets	10,282
Total current assets acquired	21,183
Property and equipment	3,354
Goodwill	137,915
Deferred income taxes	565
Other noncurrent assets	416
Total assets acquired	251,029
Accounts payable	4,624
Employee compensation	6,046
Other current liabilities	11,683
Total current liabilities acquired	22,353
Deferred income taxes	23,427
Other noncurrent liabilities	164
Total liabilities acquired	45,944
Net assets acquired	205,085
Software | Retail Decisions [Member]
Business Acquisition [Line Items]
Amortizable intangible assets	$ 33,136
Software | Retail Decisions [Member] | Minimum
Business Acquisition [Line Items]
Acquired intangible assets, weighted-average useful lives	5 years
Software | Retail Decisions [Member] | Maximum
Business Acquisition [Line Items]
Acquired intangible assets, weighted-average useful lives	7 years
Customer relationships | Retail Decisions [Member]
Business Acquisition [Line Items]
Acquired intangible assets, weighted-average useful lives	18 years
Amortizable intangible assets	$ 50,480
Trademarks | Retail Decisions [Member]
Business Acquisition [Line Items]
Acquired intangible assets, weighted-average useful lives	5 years
Amortizable intangible assets	$ 3,980