Schedule of Information Related to Stock Repurchase Programs (Parenthetical) (Detail) (USD $)	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Withholding Obligations
Class of Stock [Line Items]
Number of shares repurchased	427,170	432,562	217,649
Shares repurchased at an average price	$ 63.68	$ 44.28	$ 45.51
Restricted Stock
Class of Stock [Line Items]
Number of shares repurchased		750
Shares repurchased at an average price		$ 0.01

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

Name:	us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration