Schedule of Cash Flow Statement Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating activities:
Net cash provided by (used in) operating activities	$ 971,438	$ 881,089
Investing activities:
Capital expenditures, including internal-use software and website development	(74,749)	(87,156)
Purchases of investments	(495,377)	(598,127)
Sales and maturities of investments	135,669	245,244
Acquisitions, net of cash acquired		(540,489)
Other, net	854	5,808
Net cash used in investing activities	(433,603)	(974,720)
Financing activities:
Purchases of treasury stock	(121,865)	(117,672)
Proceeds from issuance of treasury stock		25,273
Other, net	43,661	14,048
Net cash used in financing activities	(78,204)	(78,351)
Effect of exchange rate changes on cash and cash equivalents	3,402	(38,381)
Net increase (decrease) in cash and cash equivalents	463,033	(210,363)
Cash and cash equivalents at beginning of period	1,021,033	1,293,161
Cash and cash equivalents at end of period	1,484,066	1,082,798
Parent
Financing activities:
Purchases of treasury stock	(121,865)	(117,672)
Proceeds from issuance of treasury stock		25,273
Transfers (to) from related parties	82,239	70,918
Other, net	39,626	21,481
Guarantor Subsidiaries
Operating activities:
Net cash provided by (used in) operating activities	907,990	905,757
Investing activities:
Capital expenditures, including internal-use software and website development	(62,763)	(57,350)
Purchases of investments	(399,521)	(532,019)
Sales and maturities of investments	56,398	166,023
Other, net	1,358	5,808
Net cash used in investing activities	(404,528)	(417,538)
Financing activities:
Transfers (to) from related parties	(82,239)	(690,735)
Other, net	3,794	(7,750)
Net cash used in financing activities	(78,445)	(698,485)
Effect of exchange rate changes on cash and cash equivalents	2,433	(37,808)
Net increase (decrease) in cash and cash equivalents	427,450	(248,074)
Cash and cash equivalents at beginning of period	606,683	1,007,156
Cash and cash equivalents at end of period	1,034,133	759,082
Non-Guarantor Subsidiaries
Operating activities:
Net cash provided by (used in) operating activities	63,448	(24,668)
Investing activities:
Capital expenditures, including internal-use software and website development	(11,986)	(29,806)
Purchases of investments	(95,856)	(66,108)
Sales and maturities of investments	79,271	79,221
Acquisitions, net of cash acquired		(540,489)
Other, net	(504)
Net cash used in investing activities	(29,075)	(557,182)
Financing activities:
Transfers (to) from related parties		619,817
Other, net	241	317
Net cash used in financing activities	241	620,134
Effect of exchange rate changes on cash and cash equivalents	969	(573)
Net increase (decrease) in cash and cash equivalents	35,583	37,711
Cash and cash equivalents at beginning of period	414,350	286,005
Cash and cash equivalents at end of period	$ 449,933	$ 323,716