Fair Value Measurements - Valuation of Financial Instruments That are Marked-to-Market on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets
Estimated Fair Value	$ 2,020,948	$ 487,669
Total earning assets	3,047,226
Fair Value Measurements on a Recurring Basis
Assets
Estimated Fair Value	2,020,948	487,669
Derivative instruments	185	715
Total earning assets	2,021,133	488,384
Liabilities
Derivative instruments	(179)	(1,164)
Fair Value Measurements on a Recurring Basis | Level 1
Assets
Estimated Fair Value	0	0
Derivative instruments	0	0
Total earning assets	0	0
Liabilities
Derivative instruments	0	0
Fair Value Measurements on a Recurring Basis | Level 2
Assets
Estimated Fair Value	1,947,062	487,669
Derivative instruments	185	715
Total earning assets	1,947,247	488,384
Liabilities
Derivative instruments	(179)	(1,164)
Fair Value Measurements on a Recurring Basis | Level 3
Assets
Estimated Fair Value	73,886	0
Derivative instruments	0	0
Total earning assets	73,886	0
Liabilities
Derivative instruments	$ 0	$ 0