Business Combination - Dynamic Clinical Systems, Inc (Details) - USD ($)		12 Months Ended
	Apr. 24, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Acquisitions
Acquisitions of businesses, net of cash acquired		$ 12,146,000	$ 28,177,000	$ 2,813,000
Preliminary allocation of fair value of the acquisition:
Goodwill		$ 411,203,000	402,934,000	$ 385,750,000	$ 384,341,000
Dynamic Clinical Systems, Inc
Business Acquisitions
Acquisitions of businesses, net of cash acquired	$ 3,300,000
Preliminary allocation of fair value of the acquisition:
Current assets			186,000
Goodwill			2,162,000
Intangibles:
Total assets acquired			4,188,000
Liabilities assumed:
Deferred revenue			210,000
Other current liabilities			302,000
Deferred income tax liability			358,000
Net assets acquired			3,318,000
Dynamic Clinical Systems, Inc | Trade names
Intangibles:
Intangibles			100,000
Dynamic Clinical Systems, Inc | Customer relationships
Intangibles:
Intangibles			1,200,000
Dynamic Clinical Systems, Inc | Proprietary technology
Intangibles:
Intangibles			380,000
Dynamic Clinical Systems, Inc | Other
Intangibles:
Intangibles			160,000
Earnout feature | Dynamic Clinical Systems, Inc
Contingent consideration
Contingent consideration	$ 0
General and administrative | Dynamic Clinical Systems, Inc
Other information
Transaction expenses			$ 118,000