Dividend - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jun. 19, 2015	May. 21, 2015
Equity [Abstract]
Cash dividend authorized		$ 1.50
Special cash dividend paid	$ 26.0
Dividend paid date		Jun. 19, 2015
Dividend paid date of record		Jun. 05, 2015

Cash outflow to owners or shareholders, excluding ordinary dividends. Includes special dividends.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration