Business Combinations - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Aggregate purchase price of acquisitions	$ 1,324,000	$ 1,071,000
Cash payment for acquisition	1,013,000	61,000
Assumption of liabilities	31,000	43,000
Recorded earn-out payables	280,000
Average annual operating profit earned period, minimum (years)	1 year
Average annual operating profit earned period, maximum (years)	3 years
Aggregate purchase price of acquisitions	21,000
Total goodwill	318,000
Goodwill currently deductible for income tax purposes	38,000
Goodwill related to the recorded earn-out payables	280,000
Total revenues related to acquisitions	6,000
Income before income taxes related to acquisitions	1,000
Other payables for acquisition		454,000
Recorded earn-out payable	280,000	(721,000)
Maximum future contingency payments related to acquisitions	125,006,000
Percentage recognition by acquirer of fair value of acquired assets	100.00%
Future earnings of acquired entities, term basis of potential earn-out obligations, minimum (years)	1 year
Future earnings of acquired entities, term basis of potential earn-out obligations, maximum (years)	3 years
Estimated acquisition earn-out payables	48,806,000	49,469,000	43,058,000	52,987,000
Accounts Payable [Member]
Business Acquisition [Line Items]
Estimated acquisition earn-out payables	18,171,000
Purchased customer accounts [Member]
Business Acquisition [Line Items]
Weighted average life (years)	15 years
Non-compete agreements [Member]
Business Acquisition [Line Items]
Weighted average life (years)	5 years
Other Non-Current Liability [Member]
Business Acquisition [Line Items]
Estimated acquisition earn-out payables	$ 30,635,000
Asset Acquisitions [Member]
Business Acquisition [Line Items]
Number of acquisitions	1