Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income to shareholders	$ 18,961	$ 17,168	$ 40,827	$ 35,819
Weighted average common shares outstanding:
Basic (in shares)	28,735,087	28,540,350	28,608,398	28,540,350
Common share equivalents (in shares)	683,164	253,465	636,122	247,150
Diluted (in shares)	29,418,251	28,793,815	29,244,520	28,787,500
Earnings per share:
Basic (in dollars per share)	$ 0.66	$ 0.60	$ 1.43	$ 1.26
Common share equivalents (in dollars per share)	(0.02)		(0.03)	(0.02)
Diluted (in dollars per share)	$ 0.64	$ 0.60	$ 1.40	$ 1.24