Earnings per Share Repurchase of Common Stock (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Stock Repurchased and Retired During Period, Value	$ 14,750	$ 670	$ 2,920
10b5-1 share repurchase program [Member]
Stock Repurchase Program, Authorized Amount	$ 75,000			$ 75,000		$ 50,000
Stock Repurchased and Retired During Period, Shares	502,500		100,947	527,400	100,947
Stock Repurchased and Retired During Period, Value	$ 14,700		$ 2,900	$ 15,400	$ 2,900

Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

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