Incentive Plans - Additional Information about Stock Options Outstanding (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, No. of Options	2,920,410
Options Outstanding, Avg. Life Remaining in Years	2 years
Options Outstanding, Aggregate Intrinsic Value	$ 5,365,535
Options Exercisable, No. of Options	(2,694,410)
Options Exercisable, Avg. Life Remaining in Years	1 year 9 months 18 days
Options Exercisable, Aggregate Intrinsic Value	$ 5,365,535
Range of Exercise Prices per Option, $17.00 to $30.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices per option, lower limit		$ 17
Range of exercise prices per option, upper limit		30
Options Outstanding, No. of Options	1,033,000
Options Outstanding, Avg. Life Remaining in Years	3 years 6 months
Options Outstanding, Aggregate Intrinsic Value	$ 5,365,535
Options Exercisable, No. of Options	(807,000)
Options Exercisable, Avg. Life Remaining in Years	3 years 4 months 24 days
Options Exercisable, Aggregate Intrinsic Value	$ 5,365,535
Range of Exercise Prices per Option, $31.00 to $50.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices per option, lower limit		31
Range of exercise prices per option, upper limit		50
Options Outstanding, No. of Options	730,000
Options Outstanding, Avg. Life Remaining in Years	2 years 1 month 6 days
Options Outstanding, Aggregate Intrinsic Value	$ 0
Options Exercisable, No. of Options	(730,000)
Options Exercisable, Avg. Life Remaining in Years	2 years 1 month 6 days
Options Exercisable, Aggregate Intrinsic Value	$ 0
Range of Exercise Prices per Option, $51.00 to $65.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices per option, lower limit		51
Range of exercise prices per option, upper limit		$ 65
Options Outstanding, No. of Options	1,157,410
Options Outstanding, Avg. Life Remaining in Years	6 months
Options Outstanding, Aggregate Intrinsic Value	$ 0
Options Exercisable, No. of Options	(1,157,410)
Options Exercisable, Avg. Life Remaining in Years	15 days
Options Exercisable, Aggregate Intrinsic Value	$ 0