Earnings per Share Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Income (Loss) Attributable to Parent	$ 91,012	$ 73,537	$ 283,485	$ 159,791
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Weighted Average Number of Shares Outstanding, Basic	29,250	28,653	29,179	28,554
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Incremental Common Shares Attributable to Stock Options	447	376	474	253
Deferred Compensation Awards	331	257	313	223
Diluted Weighted Average Number of Shares Outstanding	30,028	29,286	29,966	29,030
Earnings Per Share, Basic	$ 3.11	$ 2.57	$ 9.72	$ 5.60
Earnings Per Share, Diluted	$ 3.03	$ 2.51	$ 9.46	$ 5.50
Anti-dilutive stock equivalent awards not included in the calculation of diluted loss per share	16	435	7	360