Fair Value Measurements of Assets and Liabilities (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Aggregate Amount of Unrealized Losses
Net unrealized gain (loss) net of tax reported as a component of accumulated other comprehensive (loss) income	$ 123,000	$ (207,000)	$ 17,000
Proceeds from sale of marketable securities	52,800,000
Net losses on sale of security	264,000
FusionOne Inc.
Company payments
Cash paid under agreement to former FusionOne employees	2,300,000
Sapience Knowledge Systems, Inc. (SKS)
Company payments
Cash paid to the former SKS stock-holders and employees at the completion of the earn-out-milestones	3,500,000
Level 1
Summary of assets and liabilities held by the Company and their related classifications under the fair value hierarchy
Money market funds	41,395,000	99,315,000
Level 2
Summary of assets and liabilities held by the Company and their related classifications under the fair value hierarchy
Certificates of deposit, municipal bonds and corporate bonds	15,474,000	53,261,000
Aggregate Fair Value
Due in one year or less	20,188,000	51,504,000
Due after one year, less than five years	653,000	31,642,000
Total	20,841,000	83,146,000
Aggregate Amount of Unrealized Gains
Due in one year or less	18,000	59,000
Due after one year, less than five years	1,000	76,000
Total	19,000	135,000
Aggregate Amount of Unrealized Losses
Due in one year or less	(41,000)	(315,000)
Due after one year, less than five years	(1,000)	(48,000)
Total	(42,000)	(363,000)
Level 3
Summary of assets and liabilities held by the Company and their related classifications under the fair value hierarchy
Contingent consideration obligation	(8,379,000)	(13,167,000)
Total
Summary of assets and liabilities held by the Company and their related classifications under the fair value hierarchy
Fair value of net assets	$ 48,490,000	$ 139,409,000