Earnings per Share Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net Income (Loss) Attributable to Parent	$ 54,508	$ 30,246	$ 86,254	$ 47,969
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Weighted Average Number of Shares Outstanding, Basic	28,531	27,599	28,504	27,549
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Stock Options	115	308	210	276
Deferred Compensation Awards	190	183	206	202
Diluted Weighted Average Number of Shares Outstanding	28,836	28,090	28,920	28,027
Earnings Per Share, Basic	$ 1.91	$ 1.10	$ 3.03	$ 1.74
Earnings Per Share, Diluted	$ 1.89	$ 1.08	$ 2.98	$ 1.71
Anti-dilutive stock equivalent awards not included in the calculation of diluted loss per share	1,178	412	676	714