Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) (Unaudited) - $ / shares	3 Months Ended	12 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Dividend declared (in dollars per share)	$ 0.2875	$ 1.1325
Deferred compensation plan held Rabbi Trust (shares)	75,959	70,631
Shares issued under the performance incentive plan withheld for employee taxes (shares)	12,031	12,620

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: 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

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration