Earnings per Share Repurchase of Common Stock (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock Repurchased and Retired During Period, Value			$ 3,590
10b5-1 share repurchase program [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased	50,000,000		50,000,000
Stock Repurchased and Retired During Period, Shares	23,191	0	124,138	0
Stock Repurchased and Retired During Period, Value	$ 700	$ 0	$ 3,600	$ 0

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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