Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net Income	$ 46,415	$ 40,769	$ 128,134	$ 97,100
Earnings allocated to participating securities - preferred shares	0	0	0	4
Earnings allocated to participating securities - nonvested restricted shares	504	558	1,413	1,325
Earnings allocated to common shareholders, Basic	$ 45,911	$ 40,211	$ 126,721	$ 95,771
Weighted average common shares outstanding	72,427	57,566	72,370	57,459
Basic earnings per common share	$ 0.63	$ 0.70	$ 1.75	$ 1.67
Earnings allocated to common shareholders, Diluted	$ 45,911	$ 40,211	$ 126,721	$ 95,771
Dilutive effect of equity awards and warrants	5	5	4	6
Weighted average diluted common shares outstanding	72,432	57,571	72,374	57,465
Diluted earnings per common share	$ 0.63	$ 0.70	$ 1.75	$ 1.67
Potentially dilutive share options that were not included in the computation of diluted EPS because to do so would be anti-dilutive.	0	12	5	13