Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities
Net income	$ 25,614	$ 18,588
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,286	2,909
Amortization of debt issuance costs	23	32
Stock-based compensation expense	3,625	1,223
Deferred income taxes, net	(4,480)	(3,644)
Changes in operating assets and liabilities:
Accounts receivable	(508)	(226)
Prepaid expenses	(938)	(1,262)
Inventory	176	423
Deposits and other assets	(154)	420
Accounts payable	(1,349)	(1,170)
Income taxes, net	17,269	13,325
Accrued commissions and bonuses	(5,277)	(6,903)
Accrued payroll and vacation	2,919	2,339
Deferred revenue	2,455	1,783
Accrued expenses and other current liabilities	(3,436)	2,111
Net cash provided by operating activities	40,225	29,948
Cash flows from investing activities
Increase in funds held for clients	(92,736)	(428,916)
Purchases of property and equipment	(9,136)	(8,363)
Net cash used in investing activities	(101,872)	(437,279)
Cash flows from financing activities
Proceeds from issuance of long-term debt	2,093
Principal payments on long-term debt	(282)	(224)
Increase in client funds obligation	92,736	428,916
Payment of debt issuance costs	(143)
Net cash provided by financing activities	94,404	428,692
Net increase in cash and cash equivalents	32,757	21,361
Cash and cash equivalents
Beginning of period	60,158	50,714
End of period	$ 92,915	$ 72,075