Loans Receivable and Allowance for Credit Losses (Schedule of Allowance for Loan Losses by Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 101,466	$ 55,525
Provision benefit to operations	(15,000)	14,700
Retained earnings (due to initial CECL adoption)		7,920
Recoveries of loans previously charged-off	1,107	529
Loans charged-off	(1,982)	(3,531)
Balance at end of period	85,591	75,143
Mortgage Portfolio Segment
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	68,307	25,511
Provision benefit to operations	(13,467)	7,710
Retained earnings (due to initial CECL adoption)		14,188
Recoveries of loans previously charged-off	276	93
Loans charged-off	(918)	(2)
Balance at end of period	54,198	47,500
Commercial Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	27,084	28,263
Provision benefit to operations	(467)	7,619
Retained earnings (due to initial CECL adoption)		(9,974)
Recoveries of loans previously charged-off	528	313
Loans charged-off	(843)	(3,380)
Balance at end of period	26,302	22,841
Consumer Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	6,075	1,751
Provision benefit to operations	(1,066)	(629)
Retained earnings (due to initial CECL adoption)		3,706
Recoveries of loans previously charged-off	303	123
Loans charged-off	(221)	(149)
Balance at end of period	$ 5,091	$ 4,802