Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net income	$ 38,436	$ 26,517	$ 13,932
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization of property and equipment	23,571	16,975	12,174
Amortization of intangibles	11,259	6,264	2,837
Amortization of deferred financing costs and debt discount	383	264	159
Provision for doubtful accounts	2,928	919	1,900
Write-off of debt issuance costs	286		233
Gain on sale of property and equipment	(254)	(409)	(460)
Gain on bargain purchase		(1,116)
Noncash stock compensation	1,894	2,116	300
Deferred income taxes	(605)	(1,515)	(378)
Other			(490)
Changes in assets and liabilities, excluding effects of acquisitions
Accounts receivable	(18,760)	(17,526)	(10,688)
Inventories	(8,677)	(2,846)	(2,925)
Other assets	2,803	823	(5,121)
Accounts payable	12,400	(2,511)	4,585
Income taxes payable/receivable	1,484	3,592	(1,678)
Other liabilities	6,118	3,000	5,222
Net cash provided by operating activities	73,266	34,547	19,602
Cash flows from investing activities
Restricted cash			1,708
Purchases of property and equipment	(27,013)	(27,305)	(6,176)
Acquisitions of businesses, net of cash acquired of $2,181, $926 and $53 in 2016, 2015 and 2014, respectively	(53,312)	(84,274)	(12,364)
Proceeds from sale of property and equipment	691	634	689
Other	37	(420)
Net cash used in investing activities	(79,597)	(111,365)	(16,143)
Cash flows from financing activities
Proceeds from initial public offering of common stock, net of costs			87,645
Proceeds from secondary public offering of common stock, net of costs			14,418
Redemption of Redeemable Preferred Stock			(75,735)
Proceeds from revolving line of credit under credit agreement applicable to respective period (Note 5)	37,975	149,350
Payments on revolving line of credit under credit agreement applicable to respective period (Note 5)	(37,975)	(149,350)
Net payments on a previous revolving line of credit			(27,269)
Proceeds from term loan under credit agreement applicable to respective period (Note 5)	100,000	50,000	25,000
Payments on term loan under credit agreement applicable to respective period (Note 5)	(51,875)	(24,688)
Proceeds from delayed draw term loan under credit agreement applicable to respective period (Note 5)	12,500	50,000
Payments on delayed draw term loan under credit agreement applicable to respective period (Note 5)	(50,000)
Proceeds from vehicle and equipment notes payable	22,948	21,334
Debt issuance costs	(1,238)	(758)	(714)
Principal payments on long term debt	(5,849)	(4,088)	(1,081)
Principal payments on capital lease obligations	(8,598)	(9,674)	(9,364)
Acquisition-related obligations	(3,057)	(3,151)
Payments for deferred initial public offering costs			(4,254)
Payments for deferred secondary public offering costs			(126)
Repurchase of common stock		(6,100)	(5,283)
Surrender of common stock by employees	(836)
Net cash provided by financing activities	13,995	72,875	3,237
Net change in cash	7,664	(3,943)	6,696
Cash at beginning of year	6,818	10,761	4,065
Cash at end of year	14,482	6,818	10,761
Supplemental disclosures of cash flow information Net cash paid during the year for:
Interest	5,342	3,287	2,669
Income taxes, net of refunds	18,929	13,493	9,134
Supplemental disclosure of noncash investing and financing activities
Vehicles capitalized under capital leases and related lease obligations	3,737	3,379	14,583
Seller obligations in connection with acquisition of businesses	4,459	13,180	3,544
Unpaid purchases of property and equipment included in accounts payable	$ 775	$ 220	$ 421