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	$ 72,270	$ 50,235
Adjustments to reconcile net income to net cash provided by operating activities	(32,795)	(11,011)
Net cash provided by operating activities	39,475	39,224
Cash flows from investing activities:
Additions to property and equipment	(1,744)	(12,116)
Additions to capitalized software	(6,048)	(9,277)
Purchases of marketable securities	(11,578)	(9,646)
Prepayments and maturities of marketable securities	9,835	10,464
Sales of marketable securities	4,211	720
Purchases of other investments	20	0
Sale of subsidiary, net of cash transferred (See Note 13)	(26,694)	0
Net cash used in investing activities	(31,998)	(19,855)
Cash flows from financing activities:
Purchase and retirement of common stock	(34,466)	(36,463)
Proceeds from issuance of common stock	24,278	12,362
Tax benefit on stock options exercised	2,563	(1,609)
Payment of dividends	0	(26,518)
Net cash used in financing activities	(7,625)	(52,228)
Net decrease in cash and cash equivalents	(148)	(32,859)
Cash and cash equivalents, beginning of period	452,247	420,986
Cash and cash equivalents, end of period	$ 452,099	$ 388,127