Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate 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 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 SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30, 31
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

Name:	us-gaap_StockRepurchasedDuringPeriodValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Equity (Detail) - USD ($) shares in Millions	12 Months Ended
Equity (Detail) - USD ($) shares in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jul. 01, 2015
Stock Repurchase [Line Items]
Repurchase of common stock	$ 4,997,000	$ 25,036,000	$ 122,000
Common Stock [Member]
Stock Repurchase [Line Items]
Stock repurchase program, authorized amount (in shares)				$ 25,000,000.0
Repurchase of common stock (in shares)	0.3
Repurchase of common stock	$ 5,000,000