Share-based Compensation - Nonvested Options (Details) - Nonvested Option Shares - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Nonvested Awards, Number of Shares [Roll Forward]
Nonvested awards, beginning balance (in shares)	81,750	76,500	74,625
Granted (in shares)	66,000	42,000	42,000
Vested (in shares)	(28,875)	(36,750)	(40,125)
Canceled (in shares)	(10,125)	0	0
Nonvested awards, ending balance (in shares)	108,750	81,750	76,500
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Exercise Price [Roll Forward]
Nonvested optionsm, beginning balance (in dollars per share)	$ 47.21	$ 47.99	$ 36.35
Granted (in dollars per share)	46.75	42.56	53.90
Vested (in dollars per share)	48.46	43.52	32.54
Canceled (in dollars per share)	46.66	0	0
Nonvested optionsm, ending balance (in dollars per share)	$ 46.65	$ 47.21	$ 47.99