Borrowings - Long Term Borrowings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Long-term borrowings	$ 4,354,037	$ 4,284,304
Weighted Average Interest Rate	3.07%	3.27%
Average Balance	$ 4,483,858	$ 3,893,533
Floating-rate borrowings
Line of Credit Facility [Line Items]
Long-term borrowings	$ 1,525,976	$ 1,802,609
Weighted Average Interest Rate	2.61%	3.26%
Average Balance	$ 1,731,675	$ 1,720,540
Fixed-rate borrowings
Line of Credit Facility [Line Items]
Long-term borrowings	$ 2,828,061	$ 2,481,695
Weighted Average Interest Rate	3.31%	3.28%
Average Balance	$ 2,752,183	$ 2,172,993