Reinsurance (Reinsurance Recoverables by Counterparty) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 520,111	$ 563,428
Prudential Insurance
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	277,930	310,758
Pruco Life
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	242,144	252,383
Unaffiliated
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 37	$ 287

Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.(a),6)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99404803&loc=d3e21409-158489

Name:	us-gaap_ReinsuranceRecoverables
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant