Business Segment Information - Reconciliation of Segment Income to Income before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Income	$ 174,033	$ 132,695	$ 407,408	$ 288,035
Interest and other debt expense	27,725	28,443	78,532	83,948
Income before income taxes	$ 146,308	$ 104,252	$ 328,876	$ 204,087