Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Actuarially determined long-term liability adjustments, tax	$ 19,914	$ 30,323	$ (18,101)
Shares repurchased (in shares)	708,245	0	0
Consol Coal Resources LP Units
Shares repurchased (in shares)	167,958	0

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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