Condensed Consolidated Statement of Comprehensive Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Revenue	$ 264,720,003	$ 251,651,521	$ 759,042,648	$ 753,490,776
Cost of goods sold	201,108,604	194,553,275	581,387,018	582,881,105
Gross profit	63,611,399	57,098,246	177,655,630	170,609,671
Operating expenses:
Selling, general and administrative expenses	47,220,821	46,187,034	145,304,423	146,393,186
Depreciation and amortization	4,485,119	4,387,438	12,842,347	12,931,952
Change in fair value of contingent consideration	701,086	(1,570,129)	1,690,743	(1,743,637)
Income from operations	11,204,373	8,093,903	17,818,117	13,028,170
Other income (expense):
Interest income	6,241	17,448	54,563	35,125
Interest expense	(1,131,502)	(1,079,013)	(3,382,163)	(3,082,297)
Other, net	(1,089,088)	(119,248)	(991,868)	(307,481)
Total other expense	(2,214,349)	(1,180,813)	(4,319,468)	(3,354,653)
Income before income taxes	8,990,024	6,913,090	13,498,649	9,673,517
Income tax expense	4,006,788	1,799,419	5,945,532	2,665,067
Net income	$ 4,983,236	$ 5,113,671	$ 7,553,117	$ 7,008,450
Basic earnings per share (in dollars per share)	$ 0.09	$ 0.10	$ 0.14	$ 0.13
Diluted earnings per share (in dollars per share)	$ 0.09	$ 0.10	$ 0.14	$ 0.13
Comprehensive income	$ 3,118,069	$ 525,386	$ 1,344,204	$ 3,243,783