Business Segment Information - Reconciliation of Segment Income to Income before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting [Abstract]
Income before interest and income taxes	$ 131,234	$ 68,599	$ 233,375	$ 155,341
Interest and other debt expense	25,837	28,401	50,807	55,505
Income before income taxes	$ 105,397	$ 40,198	$ 182,568	$ 99,836