Computation of Earnings per Common Share - Computation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 107,563	$ 90,839	$ 296,824	$ 269,248
Less: Dividends paid on and earnings allocated to participating securities	(1,295)	(1,073)	(3,658)	(3,245)
Earnings applicable to common stock	$ 106,268	$ 89,766	$ 293,166	$ 266,003
Weighted average common shares outstanding	461,780,959	465,357,326	462,898,726	465,400,372
Basic earnings per common share	$ 0.23	$ 0.19	$ 0.63	$ 0.57
Earnings applicable to common stock	$ 106,268	$ 89,766	$ 293,166	$ 266,003
Potential dilutive common shares	864,855	418,674	614,082	237,708
Total shares for diluted earnings per common share computation	462,645,814	465,776,000	463,512,808	465,638,080
Diluted earnings per common share and common share equivalents	$ 0.23	$ 0.19	$ 0.63	$ 0.57