Schedule of Cash Flow Statement Information (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Operating activities:
Net cash provided by operating activities	$ 1,464,942	$ 1,199,608
Investing activities:
Capital expenditures, including internal-use software and website development	(157,213)	(157,840)
Purchases of investments	(1,026,054)	(1,129,789)
Sales and maturities of investments	419,478	772,817
Acquisitions, net of cash acquired		(540,489)
Other, net	(1,204)	24,146
Net cash used in investing activities	(764,993)	(1,031,155)
Financing activities:
Purchases of treasury stock	(339,020)	(134,238)
Proceeds from issuance of treasury stock		25,273
Other, net	43,410	18,933
Net cash provided by (used in) financing activities	(295,610)	(90,032)
Effect of exchange rate changes on cash and cash equivalents	8,448	(59,765)
Net increase (decrease) in cash and cash equivalents	412,787	18,656
Cash and cash equivalents at beginning of period	1,021,033	1,293,161
Cash and cash equivalents at end of period	1,433,820	1,311,817
Parent
Financing activities:
Purchases of treasury stock	(339,020)	(134,238)
Proceeds from issuance of treasury stock		25,273
Transfers (to) from related parties	297,963	83,521
Other, net	41,057	25,444
Guarantor Subsidiaries
Operating activities:
Net cash provided by operating activities	1,355,396	1,179,852
Investing activities:
Capital expenditures, including internal-use software and website development	(129,160)	(117,537)
Purchases of investments	(803,933)	(919,107)
Sales and maturities of investments	208,017	554,098
Other, net	(915)	24,189
Net cash used in investing activities	(725,991)	(458,357)
Financing activities:
Transfers (to) from related parties	(217,796)	(704,542)
Other, net	2,422	(7,595)
Net cash provided by (used in) financing activities	(215,374)	(712,137)
Effect of exchange rate changes on cash and cash equivalents	7,628	(47,685)
Net increase (decrease) in cash and cash equivalents	421,659	(38,327)
Cash and cash equivalents at beginning of period	606,683	1,007,156
Cash and cash equivalents at end of period	1,028,342	968,829
Non-Guarantor Subsidiaries
Operating activities:
Net cash provided by operating activities	109,546	19,756
Investing activities:
Capital expenditures, including internal-use software and website development	(28,053)	(40,303)
Purchases of investments	(222,121)	(210,682)
Sales and maturities of investments	211,461	218,719
Acquisitions, net of cash acquired		(540,489)
Other, net	(289)	(43)
Net cash used in investing activities	(39,002)	(572,798)
Financing activities:
Transfers (to) from related parties	(80,167)	621,021
Other, net	(69)	1,084
Net cash provided by (used in) financing activities	(80,236)	622,105
Effect of exchange rate changes on cash and cash equivalents	820	(12,080)
Net increase (decrease) in cash and cash equivalents	(8,872)	56,983
Cash and cash equivalents at beginning of period	414,350	286,005
Cash and cash equivalents at end of period	$ 405,478	$ 342,988