Supplemental Financial Information - Supplemental Statement of Cash Flows (Additional Information) (Detail)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
3.875% senior notes due 2023
Condensed Cash Flow Statements, Captions [Line Items]
Senior notes percentage	3.875%	3.875%	3.875%
5.625% senior notes due 2043
Condensed Cash Flow Statements, Captions [Line Items]
Senior notes percentage	5.625%	5.625%	5.625%

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant