Capital Stock - Schedule of Common Stock Activity (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Common Stock Activity [Roll Forward]
Beginning balance	$ 211,806
Ending balance	213,099
Common Stock
Common Stock Activity [Roll Forward]
Beginning balance	211,806	$ 194,953
Stock compensation expense	2,745	5,606
Ending balance	213,099	200,002
Treasury Cost
Common Stock Activity [Roll Forward]
Beginning balance	296,390	296,081
Stock compensation expense	0	0
Ending balance	300,919	297,350
Restricted and performance stock awards \| Common Stock
Common Stock Activity [Roll Forward]
Restricted and performance stock awards	2,411	1,102
Restricted and performance stock awards \| Treasury Cost
Common Stock Activity [Roll Forward]
Restricted and performance stock awards	2,411	1,102
Stock options exercised \| Common Stock
Common Stock Activity [Roll Forward]
Stock compensation expense	959	545
Stock options exercised \| Treasury Cost
Common Stock Activity [Roll Forward]
Stock compensation expense	506	302
Stock Compensation Plan \| Common Stock
Common Stock Activity [Roll Forward]
Treasury shares purchased	0	0
Stock Compensation Plan \| Treasury Cost
Common Stock Activity [Roll Forward]
Treasury shares purchased	$ (7,446)	$ (2,673)

Common Stock Activity [Roll Forward]

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Value of all classes of common stock held by shareholders. May be all or portion of the number of common shares authorized. These shares exclude common shares repurchased by the entity and held as treasury shares.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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