Summary of Significant Accounting Policies (Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounting Policies [Abstract]
Net income	$ 27,913	$ 23,508
Basic earnings per share:
Income available to common stockholders, basic	$ 27,913	$ 23,508
Weighted average common shares outstanding, basic (in shares)	64,768,977	64,167,376
Income available to common stockholders, per share amount, basic (usd per share)	$ 0.43	$ 0.37
Dilutive shares (in shares)	180,465	202,229
Diluted earnings per share:
Income available to common stockholders, diluted	$ 27,913	$ 23,508
Weighted average common shares outstanding, diluted (in shares)	64,949,442	64,369,605
Income available to common stockholders, per share amount, diluted (usd per share)	$ 0.43	$ 0.37