Earnings Per Share (Details) - shares	3 Months Ended								12 Months Ended
	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, 2019		Dec. 31, 2018	Dec. 31, 2017
Basic computation	50,448,000	50,444,000	50,441,000	50,381,000	50,321,000	50,318,000	49,869,000	49,416,000	50,428,560		49,984,562	48,557,599
Performance and restricted share awards (1)									323,298	[1]	252,909	97,722
Diluted computation									50,751,858		50,237,471	48,655,321

[1] Performance share awards are included in diluted weighted average number of shares outstanding based upon what would be issued if the end of the most recent reporting period was the end of the term of the award.