Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
OPERATING ACTIVITIES:
Net loss	$ (25,873)	$ (26,444)	$ (7,348)
Adjustments to reconcile net loss to net cash provided by operating activities:
Stock-based compensation expense	9,736	11,814	12,306
Depreciation	12,011	12,114	9,071
Impairment on investments	2,600	0	0
Amortization of tenant allowance	(180)	0	0
Amortization of purchased intangibles	6,673	8,040	5,090
Change in fair value of contingent consideration	0	(3,680)	0
Provision for doubtful accounts, net	1,831	2,361	1,843
Deferred income taxes	1,852	14,456	(1,736)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(3,265)	(1,368)	(1,354)
Prepaid expenses and other current assets	3,845	724	(4,056)
Other assets	196	130	614
Accounts payable	185	(1,916)	(1,528)
Accrued expenses	2,982	1,193	576
Deferred revenue	13,283	1,869	2,710
Other liabilities	(1,316)	2,538	(515)
Net cash provided by operating activities	24,560	21,831	15,673
INVESTING ACTIVITIES:
Purchases of property and equipment, including capitalized software	(12,344)	(12,980)	(10,589)
Payments for acquisitions and intangible assets, net of cash acquired	(555)	(150)	(40,871)
Cash held as collateral	1,447	(5,409)	0
Investment in technology licenses	0	0	(3,451)
Net cash used in investing activities	(11,452)	(18,539)	(54,911)
FINANCING ACTIVITIES:
Repurchase of common stock	(9,967)	(4,202)	(12,980)
Excess tax benefit from the exercise of employee stock options	0	797	664
Payments related to contingent consideration	0	(2,883)	0
Proceeds from issuance of common stock in connection with the exercise of options	2,899	4,401	9,314
Net cash used in financing activities	(7,068)	(1,887)	(3,002)
EFFECT OF FOREIGN EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(3,954)	(1,974)	(294)
CHANGE IN CASH AND CASH EQUIVALENTS	2,086	(569)	(42,534)
CASH AND CASH EQUIVALENTS - Beginning of the year	48,803	49,372	91,906
CASH AND CASH EQUIVALENTS - End of the year	50,889	48,803	49,372
SUPPLEMENTAL DISCLOSURE OF OTHER CASH FLOW INFORMATION:
Cash paid for income taxes	424	1,882	4,386
SUPPLEMENTAL DISCLOSURE OF NON CASH INVESTING AND FINANCING ACTIVITIES:
Purchase of property and equipment recorded in accounts payable	2,497	1,926	964
Leasehold improvements funded by landlord	1,440	326	0
Contact At Once! [Member]
Adjustments to reconcile net loss to net cash provided by operating activities:
Change in fair value of contingent consideration		3,200
SUPPLEMENTAL DISCLOSURE OF NON CASH INVESTING AND FINANCING ACTIVITIES:
Issuance of 1,627,753 shares of common stock in connection with the acquisition of CAO! on November 7, 2014	0	0	20,121
Contingent earn-out in connection with the acquisition of Engage paid in common stock recorded in accrued expenses	0	0	4,220
Synchronite, LLC [Member]
FINANCING ACTIVITIES:
Payments related to contingent consideration	(1,600)
SUPPLEMENTAL DISCLOSURE OF NON CASH INVESTING AND FINANCING ACTIVITIES:
Contingent earn-out in connection with the acquisition of Engage paid in common stock recorded in accrued expenses	$ 0	$ 0	$ 1,810