Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern 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.

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

Shareholders' Equity, Other Comprehensive Income and Earnings Per Share - Shareholders' Equity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Repurchase Program
Common stock
Share repurchase program, maximum amount authorized to be repurchased	$ 1,110
Shares repurchased	21,232
Restricted Stock Tax Withholding Repurchases \| Common
Common stock
Shares repurchased	7,982	9,899	9,169