Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares |
12 Months Ended | ||
---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
Common dividends, per share | $ 1.60 | $ 1.525 | $ 1.50 |
Deltic [Member] | Special Distribution [Member] | |||
Common dividends, per share | $ 3.54 |