Reconciliation of Changes in Contingent Earn-Out Obligations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Business Combination Segment Allocation [Line Items]
Beginning balance	$ 292,042
Contingent earn-out obligations associated with acquisitions	12,152
Other tax-related adjustments	2,667
Ending balance	28,058
HealthCare Partners (HCP)
Business Combination Segment Allocation [Line Items]
Remeasurement of fair value	(56,977)
Payments of the contingent earn-outs	(205,704)
All Others
Business Combination Segment Allocation [Line Items]
Remeasurement of fair value	(15,742)
Payments of the contingent earn-outs	$ (380)