Earnings Per Common Share and Share Awards Summary of Information of Fixed Stock Options (Details) - SARs - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number Of Shares, Outstanding Beginning Balance	28	25	25
Number Of Shares, SARs granted	4	4	4
Number Of Shares, SARs exercised	(2)	(1)	(4)
Number Of Shares, Outstanding Ending Balance	30	28	25	25
Number Of Shares, Exercisable as of December 31, 2019	29
Number Of Shares, Unvested as of December 31, 2019	1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted Average Exercise Price, Outstanding Beginning Balance	$ 110.27	$ 93.40	$ 65.85
Weighted Average Exercise Price, SARs granted	162.81	188.71	192.71
Weighted Average Exercise Price, SARs exercised	50.50	41.50	36.38
Weighted Average Exercise Price, Outstanding Ending Balance	124.13	$ 110.27	$ 93.40	$ 65.85
Weighted Average Exercise Price, Exercisable as of December 31, 2019	122.62
Weighted Average Exercise Price, Unvested as of December 31, 2019	$ 162.81
Average Remaining Contractual Term, Outstanding Beginning Balance	3 years 6 months 10 days	3 years 7 months 20 days	3 years 11 months 23 days	3 years 10 months 6 days
Average Remaining Contractual Term, Exercisable as of December 31, 2019	3 years 5 months 1 day
Average Remaining Contractual Term, Unvested as of December 31, 2019	6 years 4 months 17 days
Aggregate Intrinsic Value, Outstanding Beginning Balance	$ 2,019	$ 2,624	$ 837
Aggregate Intrinsic Value, Outstanding Ending Balance	1,352	$ 2,019	$ 2,624	$ 837
Aggregate Intrinsic Value, Exercisable as of December 31, 2019	1,352
Aggregate Intrinsic Value, Unvested as of December 31, 2019	$ 0