Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenue	$ 383,494	$ 361,254	$ 929,017	$ 868,780
Cost of sales	285,784	270,567	693,627	649,551
Gross profit	97,710	90,687	235,390	219,229
Selling, general, and administrative expenses	68,968	64,089	187,436	172,994
Income from operations	28,742	26,598	47,954	46,235
Interest expense	2,936	2,499	8,485	7,881
Income before income tax provision	25,806	24,099	39,469	38,354
Income tax provision	6,719	6,723	10,169	10,582
Net income	$ 19,087	$ 17,376	$ 29,300	$ 27,772
Basic net income per common share	$ 0.86	$ 0.78	$ 1.30	$ 1.25
Diluted net income per common share	$ 0.84	$ 0.75	$ 1.26	$ 1.21
Weighted average number of common shares used in computing net income per common share:
Basic	22,243,895	22,399,079	22,619,802	22,185,736
Diluted	22,821,202	23,182,546	23,212,983	22,944,581