Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income	$ 10,732	$ 24,467	$ 59,701	$ 61,326
Net income allocated to participating securities	36	0	78	0
Net income allocated to common shareholders	$ 10,696	$ 24,467	$ 59,623	$ 61,326
Weighted average common shares - issued (in shares)	49,107,000	38,123,000	41,881,000	35,384,000
Average unvested restricted share awards (in shares)	(163,000)	0	(55,000)	0
Weighted average common shares outstanding - basic (in shares)	48,944,000	38,123,000	41,826,000	35,384,000
Effect of dilutive securities
Weighted average common stock equivalents (in shares)	687,000	270,000	493,000	246,000
Denominator for diluted earnings per common share (in shares)	49,631,000	38,393,000	42,319,000	35,630,000
EPS available to common shareholders
Basic earnings per common share (dollars per share)	$ 0.22	$ 0.64	$ 1.43	$ 1.73
Diluted earnings per common share (dollars per share)	$ 0.21	$ 0.64	$ 1.40	$ 1.72
Stock Option [Member]
Earnings Per Common Share (Textual)
Average number of exercisable employee stock option awards that were not included in the computation of diluted earnings per common share (in shares)	0	17,333	0	73,028