Earnings per Share (Details) - $ / shares	3 Months Ended												12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share, Basic and Diluted [Abstract]
Basic earnings per common share (in dollars per share)	$ 0.64	$ 0.81	$ 0.77	$ 0.81	$ 0.71	$ 0.67	$ 0.95	$ 0.84	$ 0.27	$ 0.93	$ 0.93	$ 0.83	$ 3.03	$ 3.17	$ 2.97
Diluted earnings per common share (in dollars per share)	$ 0.64	$ 0.80	$ 0.76	$ 0.81	$ 0.71	$ 0.67	$ 0.94	$ 0.84	$ 0.27	$ 0.92	$ 0.92	$ 0.83	$ 3.02	$ 3.16	$ 2.95
Basic weighted average shares outstanding (in shares)													30,510,000	30,511,000	31,393,000
Diluted weighted average shares outstanding (in shares)													30,571,000	30,594,000	31,534,000
Antidilutive securities excluded from computation (in shares)													181,875	181,875	42,000
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Basic weighted average shares outstanding (in shares)													30,510,000	30,511,000	31,393,000
Incremental shares for common stock equivalents (in shares)													61,000	83,000	141,000
Diluted shares outstanding (in shares)													30,571,000	30,594,000	31,534,000