Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 47,604	$ 23,605
Net income allocated to participating securities	226	0
Net income allocated to common shareholders	$ 47,378	$ 23,605
Weighted average common shares - issued (in shares)	70,969,000	38,198,000
Average unvested restricted share awards (in shares)	(341,000)	0
Weighted average common shares outstanding - basic (in shares)	70,628,000	38,198,000
Effect of dilutive securities
Weighted average common stock equivalents (in shares)	787,000	323,000
Weighted average common shares outstanding - diluted (in shares)	71,415,000	38,521,000
EPS available to common shareholders
Basic earnings per common share (dollars per share)	$ 0.67	$ 0.61
Diluted earnings per common share (dollars per share)	0.67	0.60
Average stock valuation (in dollars per share)	$ 51.81	$ 33.29
Stock Option
Schedule Of Earnings Per Share By Common Class [Line Items]
Average number of exercisable employee stock option awards that were not included in the computation of diluted earnings per common share (in shares)	0	121,050