Subsequent Event - Additional Information (Detail) - Subsequent Event - Underwriting Agreement $ in Millions	Mar. 02, 2017 USD ($)
5.250% Notes due 2045
Subsequent Event [Line Items]
Debt instrument, aggregate principal amount	$ 50.0
Debt instrument, interest rate	5.25%
3.750% Notes due 2027
Subsequent Event [Line Items]
Debt instrument, aggregate principal amount	$ 400.0
Debt instrument, interest rate	3.75%

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant