Consolidated Statements of Cash Flows (Unaudited) - USD ($)
6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Operating activities    
Net income $ 2,193,380 $ 2,646,149
Adjustments to reconcile net income to net cash provided by operating activities:    
Deferred income taxes 2,150,016 (929,157)
Noncash stock compensation expense 9,109,921 4,504,835
Noncash interest expense 3,752,278 1,264,153
Change in contingent consideration due to seller (152,954) 164,755
Change in contingent consideration due from seller 32,006 0
Depreciation and amortization 15,127,709 9,124,157
Change in assets, net of acquisitions:    
Accounts receivable (32,242,597) (16,168,721)
Income taxes receivable (2,366,337) (170,379)
Prepaid expenses and other assets 710,372 (530,094)
Change in liabilities, net of acquisitions:    
Accounts payable 29,156,839 35,763,013
Accrued expenses and other liabilities 5,934,492 (1,001,712)
Net cash provided by operating activities 33,405,125 34,666,999
Investing activities    
Purchases of property and equipment (12,827,953) (6,578,938)
Payments for acquisitions, net of cash acquired 0 (390,538,011)
Net cash used in investing activities (12,827,953) (397,116,949)
Financing activities    
Tax benefit of stock options exercised 295,985 1,387,591
Receipt of contingent consideration due from seller 750,000 0
Payment of contingent consideration due to seller (2,086,243) (2,945,833)
Proceeds from exercise of stock options 53,158 866,323
Employee tax withholdings related to net share settlements of equity-based awards (4,627,486) (1,624,229)
Purchases of treasury stock (31,370,210) 0
Proceeds from borrowing on line of credit 0 34,782,500
Repayments of amounts borrowed on line of credit 0 (34,782,500)
Proceeds from borrowing on ABL facility 11,000,000 35,000,000
Repayments of amounts borrowed on ABL facility (11,000,000) (5,000,000)
Proceeds from sale of common stock, net of underwriting discounts and commissions 0 158,412,500
Proceeds from issuance of convertible notes, net of underwriting discounts and commissions 0 223,100,000
Payment of common stock and debt issuance costs 0 (4,133,851)
Payment to former owners of One Stop Logistics 0 (17,507,500)
Net cash (used in) provided by financing activities (36,984,796) 387,555,001
(Decrease) Increase in cash and cash equivalents (16,407,624) 25,105,051
Cash and cash equivalents, beginning of period 56,522,194 32,542,119
Cash and cash equivalents, end of period 40,114,570 57,647,170
Supplemental disclosure of cash flow information    
Cash paid during the year for interest 3,586,933 2,165,738
Cash paid for income taxes 1,665,710 1,867,055
Noncash investing activity    
Issuance of common stock in connection with Command acquisition 0 14,746,000
Noncash financing activity    
Fair value of due to seller obligation at acquisition date 0 1,500,000
Liability for purchases of treasury stock not yet settled $ 1,729,327 $ 0