CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Revenues	$ 264,482	$ 200,045
Operating expenses:
Cost of revenues (exclusive of depreciation and amortization)	167,381	125,887
Selling, general and administrative expenses	61,494	46,938
Depreciation and amortization expense	5,102	4,200
Other operating expense, net	174	200
Income from operations	30,331	22,820
Interest and other income, net	1,211	1,158
Foreign exchange loss	(1,290)	(5,754)
Income before provision for income taxes	30,252	18,224
Provision for income taxes	6,353	3,510
Net income	23,899	14,714
Foreign currency translation adjustments	4,699	(2,730)
Comprehensive income	$ 28,598	$ 11,984
Net income per share:
Basic (in dollars per share)	$ 0.48	$ 0.31
Diluted (in dollars per share)	$ 0.45	$ 0.29
Shares used in calculation of net income per share:
Basic (in shares)	49,714	47,886
Diluted (in shares)	52,883	51,000