Long Term Debt - Components of Long-term Debt (Parenthetical) (Detail)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Debt Instrument [Line Items]
Interest rate on Senior Notes	5.25%
5.25% Senior Notes due March 15, 2019 [Member]
Debt Instrument [Line Items]
Interest rate on Senior Notes	5.25%	5.25%
Senior Notes payable periods	Mar. 15, 2019

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: 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