Consolidated Statements of Stockholders' Equity (unaudited) (Parenthetical) - $ / shares	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Consolidated Statements of Stockholders' Equity (unaudited) [Abstract]
Cash dividends - per share (in dollars per share)	$ 0.48	$ 0.46
Net issuance of shares to employee benefit plans and other stock plans (in shares)	104,390	252,312

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant