Summary of Significant Accounting Policies - Narrative (Detail) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Accounting Policies [Line Items]
Outstanding standby letters of credit as collateral			$ 21,500,000	$ 21,500,000
Accrued revenue			18,400,000	21,900,000
Equity compensation			2,500,000	1,400,000	$ 2,100,000
Advertising costs			4,900,000	4,100,000	3,200,000
Prepaid expenses, advertising			0	1,000,000
Restructuring costs			1,274,000	840,000	484,000
Cumulative impact of currency fluctuations			1,200,000	1,100,000
Reclassification of currency translation adjustments related to sale of clinical trial services business		$ (2,300,000)	0	0	(2,336,000)
Income tax expense (benefit) related to items of other comprehensive income			0	162,000	(162,000)
Exit Costs
Significant Accounting Policies [Line Items]
Restructuring costs			88,000	1,132,000
Payments paid for exit liabilities			655,000	264,000
Restructuring reserve			46,000	868,000	0
Post-employment Benefit
Significant Accounting Policies [Line Items]
Restructuring costs			17,000	1,453,000
Payments paid for exit liabilities			732,000	691,000
Restructuring reserve			47,000	762,000	$ 0
Occurrence-Based Professional Liability Insurance | MDA Holdings Inc
Significant Accounting Policies [Line Items]
Coverage for professional liability claims	$ 500,000
Letter of credit for malpractice claims			2,000,000	5,000,000
Other Current Liabilities
Significant Accounting Policies [Line Items]
Deferred revenue			$ 1,100,000	1,200,000
Minimum
Significant Accounting Policies [Line Items]
Contract terms (in days)			15 days
Short term leases period (in months)			3 months
Estimated useful life of assets (in years)			3 years
Intangible assets- useful life (in years)			5 years
Minimum | Computer software
Significant Accounting Policies [Line Items]
Estimated useful life of assets (in years)			3 years
Maximum
Significant Accounting Policies [Line Items]
Contract terms (in days)			60 days
Short term leases period (in months)			6 months
Estimated useful life of assets (in years)			7 years
Intangible assets- useful life (in years)			16 years
Maximum | Computer software
Significant Accounting Policies [Line Items]
Estimated useful life of assets (in years)			5 years
Cost Optimization Project
Significant Accounting Policies [Line Items]
Restructuring costs			$ 1,300,000
Restructuring reserve			400,000	$ 0
Cost Optimization Project | Contract Termination
Significant Accounting Policies [Line Items]
Restructuring costs			100,000
Payments paid for exit liabilities			100,000
Cost Optimization Project | Exit Costs
Significant Accounting Policies [Line Items]
Restructuring costs			600,000
Payments paid for exit liabilities			300,000
Restructuring reserve			300,000
Cost Optimization Project | Post-employment Benefit
Significant Accounting Policies [Line Items]
Restructuring costs			600,000
Payments paid for exit liabilities			500,000
Restructuring reserve			$ 100,000