Schedule of Cash Flow Statement Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating activities:
Net cash provided by operating activities from continuing operations	$ 881,089	$ 847,816
Investing activities:
Capital expenditures, including internal-use software and website development	(87,156)	(50,814)
Purchases of investments	(598,127)	(293,190)
Sales and maturities of investments	245,244	240,641
Acquisitions, net of cash acquired	(540,489)
Other, net	5,808	5,606
Net cash used in investing activities from continuing operations	(974,720)	(97,757)
Financing activities:
Purchases of treasury stock	(117,672)	(198,164)
Proceeds from issuance of treasury stock	25,273
Other, net	14,048	22,913
Net cash provided by (used in) financing activities from continuing operations	(78,351)	(175,251)
Net cash provided by (used in) continuing operations	(171,982)	574,808
Net cash used in discontinued operations		(7,607)
Effect of exchange rate changes on cash and cash equivalents	(38,381)	16,173
Net decrease (increase) in cash and cash equivalents	(210,363)	583,374
Cash and cash equivalents at beginning of period	1,293,161	689,134
Cash and cash equivalents at end of period	1,082,798	1,272,508
Parent
Financing activities:
Purchases of treasury stock	(117,672)	(198,164)
Proceeds from issuance of treasury stock	25,273
Transfers (to) from related parties	70,918	171,176
Other, net	21,481	26,988
Guarantor Subsidiaries
Operating activities:
Net cash provided by operating activities from continuing operations	285,940	832,140
Investing activities:
Capital expenditures, including internal-use software and website development	(57,350)	(41,917)
Purchases of investments	(532,019)	(226,114)
Sales and maturities of investments	166,023	196,501
Other, net	5,808	6,637
Net cash used in investing activities from continuing operations	(417,538)	(64,893)
Financing activities:
Transfers (to) from related parties	(70,918)	(171,176)
Other, net	(7,750)	(4,190)
Net cash provided by (used in) financing activities from continuing operations	(78,668)	(175,366)
Net cash provided by (used in) continuing operations	(210,266)	591,881
Net cash used in discontinued operations		(7,607)
Effect of exchange rate changes on cash and cash equivalents	(37,808)	13,153
Net decrease (increase) in cash and cash equivalents	(248,074)	597,427
Cash and cash equivalents at beginning of period	1,007,156	357,252
Cash and cash equivalents at end of period	759,082	954,679
Non-Guarantor Subsidiaries
Operating activities:
Net cash provided by operating activities from continuing operations	595,149	15,676
Investing activities:
Capital expenditures, including internal-use software and website development	(29,806)	(8,897)
Purchases of investments	(66,108)	(67,076)
Sales and maturities of investments	79,221	44,140
Acquisitions, net of cash acquired	(540,489)
Other, net		(1,031)
Net cash used in investing activities from continuing operations	(557,182)	(32,864)
Financing activities:
Other, net	317	115
Net cash provided by (used in) financing activities from continuing operations	317	115
Net cash provided by (used in) continuing operations	38,284	(17,073)
Effect of exchange rate changes on cash and cash equivalents	(573)	3,020
Net decrease (increase) in cash and cash equivalents	37,711	(14,053)
Cash and cash equivalents at beginning of period	286,005	331,882
Cash and cash equivalents at end of period	$ 323,716	$ 317,829