Goodwill and Purchased Intangible Assets - Goodwill Allocated to Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Goodwill [Roll Forward]
Goodwill	$ 149,142	$ 131,267
Acquisitions during the period	1,708
Adjustments	(26)
Foreign currency exchange rate effect	1,882
Goodwill	152,706	131,267
SapientNitro [Member]
Goodwill [Roll Forward]
Goodwill	118,642
Acquisitions during the period	0
Adjustments	(26)
Foreign currency exchange rate effect	1,409
Goodwill	120,025
Sapient Global Markets [Member]
Goodwill [Roll Forward]
Goodwill	30,500
Acquisitions during the period	0
Adjustments	0
Foreign currency exchange rate effect	473
Goodwill	30,973
Sapient Government Services [Member]
Goodwill [Roll Forward]
Goodwill	0
Acquisitions during the period	1,708
Adjustments	0
Foreign currency exchange rate effect	0
Goodwill	$ 1,708