Loans Receivable and Allowance for Credit Losses (Summary of Activities in Allowance for Unfunded Credit Reserves) (Details) - Allowance for Unfunded Credit Reserves - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Allowance for unfunded credit reserves
Allowance for unfunded credit reserves, beginning of period	$ 12,566	$ 13,318
Provision for unfunded credit reserves	1,939	296
Allowance for unfunded credit reserves, end of period	$ 14,505	$ 13,614

Amount of expense related to credit loss from transactions other than loan and lease transactions.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(11))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Name:	us-gaap_ProvisionForOtherCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration