Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Footnote Information) (Details) - Measured on a recurring basis - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 31,955,334	$ 14,672,330
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 192,217	161,172
Significant Unobservable Inputs (Level 3) | Noncontrolling Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		$ 120