Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 39,101	$ 32,994	$ 27,557
Adjustments to reconcile net income to net cash provided by operations:
Depreciation and amortization	13,786	12,711	10,676
Share-based compensation expense	11,653	7,411	6,253
Provision for losses - accounts receivable	729	961	805
Excess tax benefit from exercises of share-based arrangements	(28,207)	(8,764)	(3,590)
Deferred income tax benefit	(1,497)	(215)	(2,916)
Changes in operating assets and liabilities, exclusive of effects of acquired companies:
Accounts receivable	(7,488)	(6,825)	(8,544)
Income tax receivable	18,898	7,791	6,084
Prepaid expenses and other current assets	(4,154)	110	(214)
Accounts payable	(574)	(369)	575
Accrued liabilities	7,655	(530)	4,887
Deferred revenue	16,188	13,393	14,862
Net cash provided by operating activities	66,090	58,668	56,435
Cash flows from investing activities:
Proceeds from sale of investments	1,090	75	50
Cost of acquisitions, net of cash acquired	(181)	(25,680)	(17,298)
Additions to property and equipment	(26,858)	(9,102)	(12,278)
Decrease (increase) in other	291	(29)	717
Net cash used by investing activities	(25,658)	(34,736)	(28,809)
Cash flows from financing activities:
(Decrease) increase in net borrowings on revolving line of credit	(18,000)	(42,700)	34,200
Purchase of treasury shares			(71,802)
Contributions from employee stock purchase plan	3,542	2,641	2,045
Proceeds from exercise of stock options	18,289	12,443	3,553
Excess tax benefit from exercises of share-based arrangements	28,207	8,764	3,590
Net cash provided (used) by financing activities	32,038	(18,852)	(28,414)
Net increase (decrease) in cash and cash equivalents	72,470	5,080	(788)
Cash and cash equivalents at beginning of period	6,406	1,326	2,114
Cash and cash equivalents at end of period	$ 78,876	$ 6,406	$ 1,326