Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	0 Months Ended	12 Months Ended
	Dec. 05, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 20, 2013
Summary Of Significant Accounting Policies [Line Items]
Increase in number of authorized shares	100,000	200,000	200,000	200,000
Stock split ratio	2
Common stock remained		$ 0.01	$ 0.01
Long-term investments maturity, minimum years		1 year
Long-term investments maturity, maximum years		7 years
Additional cash amounts to be paid based on achievement of performance measures within period, maximum years		5 years
Intangible assets finite lives		1 year 7 months 6 days
Money market funds carrying amount		$ 5.3	$ 11.1
Cash surrender value, fair value		17.1	13.8
Contingent consideration liabilities related to acquisitions		$ 43.0	$ 37.7
Buildings [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives, years		20 years
Government Contracts Concentration Risk [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of net accounts receivable		20.00%	21.00%
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets finite lives		1 year
Minimum [Member] | Medical Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives, years		3 years
Minimum [Member] | Computer Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives, years		3 years
Minimum [Member] | Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives, years		3 years
Minimum [Member] | Furniture [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives, years		3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets finite lives		20 years
Maximum [Member] | Medical Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives, years		10 years
Maximum [Member] | Computer Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives, years		10 years
Maximum [Member] | Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives, years		10 years
Maximum [Member] | Furniture [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives, years		10 years