Stock-based Compensation - Additional Information (Detail)	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2013
Time Based Awards [Member]
Schedule Of Stock Options [Line Items]
Restricted stock units awarded to managers	3,857	5,075
Performance Based Awards [Member]
Schedule Of Stock Options [Line Items]
Restricted stock units awarded to managers	935	124,982

Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

Reference 1: 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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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