Summary of Significant Accounting Policies, Earnings Per Average Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income [Abstract]
Basic net income applicable to common stock	$ 19,368	$ 26,922
Diluted net income applicable to common stock	$ 19,368	$ 26,922
Shares [Abstract]
Basic average number of common shares outstanding (in shares)	60,528,489	60,463,693
Effect of dilutive securities [Abstract]
Add: restricted stock (LITP) (in shares)	103,021	236,392
Average number of diluted common shares outstanding (in shares)	60,631,510	60,700,085
Per Share Amount [Abstract]
Basic net income applicable to common stock (in dollars per share)	$ 0.32	$ 0.45
Diluted net income applicable to common stock (in dollars per share)	$ 0.32	$ 0.44