The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Dividends and Earnings Per Share - Dilutive Effect (Details) - shares	12 Months Ended			56 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Earnings per share
Accrued Dividend Equivalent Units	3,097			3,097
Restricted Stock Units
Earnings per share
Granted, Units				259,065
Equity Plan \| Restricted Stock Units
Earnings per share
Granted, Units	10,000	100,553	0	259,065
Accrued Dividend Equivalent Units	3,097			3,097