Valuation and Qualifying Accounts (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for doubtful accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 10,622,274	$ 10,811,026	$ 10,927,981
Charged To Income	6,760,626	2,259,690	3,236,138
Business Acquisitions
Deductions	4,115,716	2,448,442	3,353,093
Balance at End of Year	13,267,184	10,622,274	10,811,026
Tax valuation allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	28,270,571	183,911,843	176,766,238
Charged To Income	2,406,334	13,812,211	2,843,723
Charged To Equity			4,301,882
Deductions	2,684,283	169,453,483
Balance at End of Year	$ 27,992,622	$ 28,270,571	$ 183,911,843