Earnings Per Share ("EPS") (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income available to common stockholders	$ 81,826	$ 55,193		$ 185,119	$ 160,067
Average common shares outstanding (in shares)	96,608	92,290		95,090	92,246
Average potential dilutive common shares (in shares)	360	551		360	551
Average diluted common shares (in shares)	96,968	92,841		95,450	92,797
Basic earnings per share (in dollars per share)	$ 0.85	$ 0.60		$ 1.95	$ 1.74
Diluted earnings per share (in dollars per share)	$ 0.84	$ 0.59	$ 0.59	$ 1.94	$ 1.72