Loans Receivable (Summary of Allowance for Losses on Loans and Loan Impairments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of allowance for losses on loans receivable
Balance at beginning of year	$ 68,372	$ 68,372	$ 6,563
Provision for loan losses	18,690	0	62,966
Charge-offs	(18,690)	0	0
Change in present value	0	0	(1,157)
Balance at end of year	68,372	68,372	68,372
Summary of loan impairments
Balance of impaired loans at end of year				$ 188,018	$ 189,272	$ 282,882
Allowance for loan losses	(68,372)	(68,372)	(6,563)	(68,372)	(68,372)	(68,372)
Balance of impaired loans not reserved				$ 119,646	$ 120,900	$ 214,510
Average impaired loans for the year	192,728	236,077	330,216
Interest recognized on impaired loans	$ 16,235	$ 17,241	$ 27,793