Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities
Net income	$ 39,835	$ 29,009
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,993	6,118
Amortization of debt issuance costs	59	63
Net loss on disposition of property and equipment		3
Stock-based compensation expense	17,524	4,817
Deferred income taxes, net	(6,760)	(4,936)
Changes in operating assets and liabilities:
Accounts receivable	(464)	(421)
Prepaid expenses	(1,262)	(605)
Inventory	434	652
Deposits and other assets	(111)	350
Accounts payable	(319)	2,619
Income taxes, net	(2,855)	12,114
Accrued commissions and bonuses	(2,767)	(5,635)
Accrued payroll and vacation	1,088	3,640
Deferred revenue	5,293	4,675
Accrued expenses and other current liabilities	(3,395)	2,091
Net cash provided by operating activities	55,293	54,554
Cash flows from investing activities
Net change in funds held for clients	71,229	(337,611)
Purchases of property and equipment	(21,909)	(24,340)
Net cash provided by (used in) investing activities	49,320	(361,951)
Cash flows from financing activities
Proceeds from issuance of long-term debt	5,440	3,903
Repurchases of common stock	(15,187)	(3,490)
Withholding taxes paid related to net share settlement	(14,973)
Principal payments on long-term debt	(562)	(448)
Net change in client funds obligation	(71,229)	337,611
Payment of debt issuance costs	(143)
Net cash (used in) provided by financing activities	(96,654)	337,576
Increase in cash and cash equivalents	7,959	30,179
Cash and cash equivalents
Beginning of period	60,158	50,714
End of period	$ 68,117	$ 80,893