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

Share Repurchases (Details) - USD ($) $ in Thousands	9 Months Ended
Share Repurchases (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017	Oct. 31, 2018	Feb. 28, 2018
Equity, Class of Treasury Stock [Line Items]
Common stock authorized for repurchase			$ 24,000
Number of common stock repurchased (in shares)	600,000	119,007
Value of common stock repurchased	$ 15,957	$ 1,821
Maximum
Equity, Class of Treasury Stock [Line Items]
Common stock authorized for repurchase			$ 20,000	$ 20,000