Fair Value - Measurement Basis, Nonrecurring (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Total gains (losses) on assets measured at estimated fair values on a nonrecurring basis
Notes Payable	$ 1,293,625		$ 1,293,625		$ 1,292,291
Nonrecurring basis
Financial statement items measured at fair value on a nonrecurring basis
Real estate acquired in settlement of loans	8,575		8,575		2,150
Total gains (losses) on assets measured at estimated fair values on a nonrecurring basis
Real estate acquired in settlement of loans	139	$ (41)	162	$ (72)
Nonrecurring basis | Level 3
Financial statement items measured at fair value on a nonrecurring basis
Real estate acquired in settlement of loans	8,575		8,575		2,150
Fair Values
Total gains (losses) on assets measured at estimated fair values on a nonrecurring basis
Notes Payable	$ 1,306,828		$ 1,306,828		$ 1,285,894