Stock-Based Incentive Compensation Plans (Details) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Stock options [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Shares granted	27,463	481,404
Performance Shares [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Shares granted	431	156,676
Restricted Stock Units [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Shares granted	103,769	694,269
Non-employee Stock Appreciation Rights [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Shares granted		14,692
Non-employee Agent Stock Options [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Shares granted		32,400
Non-employee Director Deferred Stock Units [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Shares granted	7,845	14,498