Fair Value of Assets and Liabilities (Financial Instruments where Carrying Amounts and Fair Values May Differ) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Assets:
Policy loans	$ 1,263,413	$ 1,236,077
Cash and cash equivalents	415,497	416,840	$ 72,206	$ 212,569
Accrued investment income	93,167	88,278
Receivables from parent and affiliates	268,854	289,580
Liabilities:
Cash collateral for loaned securities	7,083	11,063
Fair Value
Assets:
Commercial mortgage and other loans	1,279,335	1,214,350
Policy loans	1,263,413	1,236,077
Cash and cash equivalents	58,863	199,894
Accrued investment income	93,167	88,278
Receivables from parent and affiliates	140,992	154,938
Other assets	29,764	28,950
Total assets	2,865,534	2,922,487
Liabilities:
Policyholders’ account balances - investment contracts	1,504,753	1,479,069
Cash collateral for loaned securities	7,083	11,063
Payables to parent and affiliates	146,207	229,345
Other liabilities	341,498	372,997
Total liabilities	1,999,541	2,092,474
Carrying Amount
Assets:
Commercial mortgage and other loans	1,225,668	1,209,150
Policy loans	1,263,413	1,236,077
Cash and cash equivalents	58,863	199,894
Accrued investment income	93,167	88,278
Receivables from parent and affiliates	140,992	154,938
Other assets	29,764	28,950
Total assets	2,811,867	2,917,287
Liabilities:
Policyholders’ account balances - investment contracts	1,505,223	1,486,929
Cash collateral for loaned securities	7,083	11,063
Payables to parent and affiliates	146,207	229,345
Other liabilities	341,498	372,997
Total liabilities	2,000,011	2,100,334
Level 1 | Fair Value
Assets:
Commercial mortgage and other loans	0	0
Policy loans	0	0
Cash and cash equivalents	42,863	56,894
Accrued investment income	0	0
Receivables from parent and affiliates	0	0
Other assets	0	0
Total assets	42,863	56,894
Liabilities:
Policyholders’ account balances - investment contracts	0	0
Cash collateral for loaned securities	0	0
Payables to parent and affiliates	0	0
Other liabilities	0	0
Total liabilities	0	0
Level 2 | Fair Value
Assets:
Commercial mortgage and other loans	0	0
Policy loans	0	0
Cash and cash equivalents	16,000	143,000
Accrued investment income	93,167	88,278
Receivables from parent and affiliates	140,992	154,938
Other assets	29,764	28,950
Total assets	279,923	415,166
Liabilities:
Policyholders’ account balances - investment contracts	1,225,951	1,206,747
Cash collateral for loaned securities	7,083	11,063
Payables to parent and affiliates	146,207	229,345
Other liabilities	341,498	372,997
Total liabilities	1,720,739	1,820,152
Level 3 | Fair Value
Assets:
Commercial mortgage and other loans	1,279,335	1,214,350
Policy loans	1,263,413	1,236,077
Cash and cash equivalents	0	0
Accrued investment income	0	0
Receivables from parent and affiliates	0	0
Other assets	0	0
Total assets	2,542,748	2,450,427
Liabilities:
Policyholders’ account balances - investment contracts	278,802	272,322
Cash collateral for loaned securities	0	0
Payables to parent and affiliates	0	0
Other liabilities	0	0
Total liabilities	$ 278,802	$ 272,322