Subsequent Event - Additional Information (Detail) (USD $)	6 Months Ended						1 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Purchased customer accounts [Member]	Jun. 30, 2012 Purchased customer accounts [Member]	Jun. 30, 2013 Non-compete agreements [Member]	Jun. 30, 2012 Non-compete agreements [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member] Well Fargo Bank Revolver [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member] Bank of America Term Loan [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member] Minimum [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member] Maximum [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member] Beecher [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member] Beecher [Member] Well Fargo Bank Revolver [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member] Beecher [Member] Bank of America Term Loan [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member] Beecher [Member] Purchased customer accounts [Member]	Jul. 01, 2013 Subsequent to January 1, 2009 [Member] Beecher [Member] Non-compete agreements [Member]
Subsequent Event [Line Items]
Aggregate purchase price of acquisitions	$ 17,865,000	$ 599,122,000										$ 454,475,000
Cash payments for acquisitions	14,366,000	428,612,000										364,644,000
Assumption of liabilities		133,938,000										89,831,000
Weighted average life (years)			15 years	15 years	5 years	5 years									15 years	5 years
Revolving and term loan													50,000,000	30,000,000
Line of credit facility drawn down amount													30,000,000
Debt instrument, maturity date								Dec. 31, 2016	Dec. 31, 2016
Increase in revolving credit facility								50,000,000
Revolving credit facility in the maximum principal amount								$ 100,000,000
Letter of credit usage fee, minimum								1.00%
Letter of credit usage fee, maximum								1.40%
LIBOR below base rate								1.00%
Availability fees, minimum								0.175%
Availability fees, maximum								0.25%
Interest rate, minimum								1.00%
Interest rate, maximum								1.40%
Adjusted LIBOR Rate							1.50%			1.00%	1.40%