SENIOR NOTES PAYABLE AND OTHER DEBT - Indebtedness of Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Scheduled maturities of borrowing arrangements and other provisions excluding capital lease obligations
2019	$ 228,879
2020	3,305,808
2021	1,257,552
2022	1,594,576
2023	1,534,501
Thereafter	6,335,453
Long-term debt and short-term borrowings, gross	14,256,769	$ 12,245,802
Line of Credit Facility and Commercial Paper Program amount outstanding	40,000
Unrestricted cash and cash equivalents	2,848,115	$ 106,363
Unsecured Revolving Credit Facility and Commercial Paper
Scheduled maturities of borrowing arrangements and other provisions excluding capital lease obligations
2019	0
2020	2,888,159
2021	0
2022	0
2023	0
Thereafter	0
Long-term debt and short-term borrowings, gross	2,888,159
Principal Amount Due at Maturity
Scheduled maturities of borrowing arrangements and other provisions excluding capital lease obligations
2019	198,730
2020	379,222
2021	1,224,542
2022	1,574,517
2023	1,520,387
Thereafter	6,240,467
Long-term debt and short-term borrowings, gross	11,137,865
Scheduled Periodic Amortization
Scheduled maturities of borrowing arrangements and other provisions excluding capital lease obligations
2019	30,149
2020	38,427
2021	33,010
2022	20,059
2023	14,114
Thereafter	94,986
Long-term debt and short-term borrowings, gross	$ 230,745