Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 9,957	$ 5,628
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of acquisition-related intangible assets		81
Depreciation & amortization	2,027	1,311
Stock-based compensation expense	878	723
Deferred income taxes	(538)	(130)
Loss on disposal of property and equipment	19	1
Changes in operating assets and liabilities:
(Increase) decrease in trade accounts receivable, net	(10,683)	1,101
(Increase) decrease in prepaid expenses & other current assets	1,160	(1,538)
(Increase) in other assets	(1)	(1)
Increase (decrease) in accounts payable	838	(1,952)
(Decrease) in accrued expenses	(2,901)	(2,107)
Increase in other current liabilities	15	38
Increase (decrease) in other long-term liabilities	485	(50)
Net cash provided by operating activities	1,256	3,105
Cash flows from investing activities:
Purchases of property and equipment	(1,002)	(1,212)
Capitalized internal use software development costs	(380)	(137)
Net cash used in investing activities	(1,382)	(1,349)
Cash flows from financing activities:
Proceeds from employee common stock purchases	904	806
Tax deductions related to stock-based compensation	581	697
Net cash provided by financing activities	1,485	1,503
Net increase in cash	1,359	3,259
Cash, beginning of period	62,358	61,639
Cash, end of period	63,717	64,898
Non-cash investing activities:
Capital expenditures accrued but not yet paid	128
Cash payments:
Income taxes paid	3,001	4,032
Cash dividends on common stock previously restricted for payment of dividend		$ 16,231