SCHEDULE I-SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) $ in Thousands	Dec. 31, 2018 USD ($)
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	$ 2,090,288
Fair Value	2,194,230
Amount at which shown in the balance sheet	2,194,230
Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	1,776,465
Fair Value	1,760,515
Amount at which shown in the balance sheet	1,760,515
Debt securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	1,776,465
Fair Value	1,760,515
Amount at which shown in the balance sheet	1,760,515
U.S. government \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	199,982
Fair Value	200,229
Amount at which shown in the balance sheet	200,229
U.S. Agency \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	31,716
Fair Value	31,904
Amount at which shown in the balance sheet	31,904
Non-U.S. govt. & agency \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	8,170
Fair Value	7,639
Amount at which shown in the balance sheet	7,639
Mtge/ABS/CMBS \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	402,992
Fair Value	395,253
Amount at which shown in the balance sheet	395,253
ABS/CMBS \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	137,224
Fair Value	136,723
Amount at which shown in the balance sheet	136,723
Corporate Debt \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	681,909
Fair Value	668,679
Amount at which shown in the balance sheet	668,679
Municipal \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	314,472
Fair Value	320,088
Amount at which shown in the balance sheet	320,088
Equity securities \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	220,373
Fair Value	340,483
Amount at which shown in the balance sheet	340,483
Ind Misc & all other \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	98,879
Fair Value	177,040
Amount at which shown in the balance sheet	177,040
ETFs (Ind/misc) \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	121,494
Fair Value	163,443
Amount at which shown in the balance sheet	163,443
Cash and Short-term Investments \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	41,690
Fair Value	41,690
Amount at which shown in the balance sheet	41,690
Other Invested Assets \| Available for sale securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	51,760
Fair Value	51,542
Amount at which shown in the balance sheet	$ 51,542

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Amount of investment held by insurance company, excluding investment in related party.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 7
-Subparagraph (SX 210.12-15(Column D))
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Cost of investment held by insurance company, excluding investment in related party.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 7
-Subparagraph (SX 210.12-15(Column B))
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-SubTopic 320
-Section S99
-Paragraph 7
-Subparagraph (SX 210.12-15(Column C))
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