CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net income	$ 42,190	$ 32,994
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation & amortization	5,074	6,712
Stock-based compensation expense	4,402	5,385
Deferred income taxes	(2,702)	(3,708)
Loss on disposal of property and equipment	7	26
Changes in operating assets and liabilities:
(Increase) in trade accounts receivable, net	(1,660)	(21,153)
Decrease in prepaid expenses & other current assets	453	3,673
(Increase) decrease in other assets	(31)	13
Increase in accounts payable	10,192	13,833
(Decrease) in accrued expenses	(2,468)	(847)
Increase (decrease) in other current liabilities	155	(432)
Increase in other long-term liabilities	1,564	475
Net cash provided by operating activities	57,176	36,971
Cash flows from investing activities:
Purchases of property and equipment	(3,927)	(3,257)
Proceeds from sale of property and equipment	6	3
Capitalized internal use software development costs	(1,762)	(624)
Net cash used in investing activities	(5,683)	(3,878)
Cash flows from financing activities:
Proceeds from employee common stock purchases	1,114	1,131
Tax deductions related to stock-based compensation	435	236
Net cash provided by financing activities	1,549	1,367
Net increase in cash	53,042	34,460
Cash, beginning of period	98,388	87,983
Cash, end of period	151,430	122,443
Non-cash investing activities:
Capital expenditures accrued but not yet paid		86
Cash payments:
Income taxes paid	17,268	$ 19,509
Cash dividends on common stock previously restricted for payment of dividend	$ 36,456