Related Party Transactions (Schedule of Base Management Fees and Performance Fees) (Details) - USD ($)	3 Months Ended												12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019
Related Party Transactions [Abstract]
Base management fees to be settled/settled in shares	$ 9,000,000	$ 8,000,000	$ 7,000,000	$ 8,000,000	$ 9,000,000	$ 12,000,000	$ 11,000,000	$ 13,000,000	$ 17,000,000	$ 18,000,000	$ 18,000,000	$ 18,000,000
Performance fees to be settled/settled in shares and cash	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Shares issued (in shares)	208,881	201,827	192,103	184,448	220,208	269,286	277,053	265,002	248,162	240,674	233,394	232,398