Fair Value of Assets and Liabilities (Financial Instruments where Carrying Amounts and Fair Values May Differ) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Assets:
Policy loans	$ 1,137,735	$ 1,123,912
Other long-term investments	333,346	298,143
Accrued investment income	93,591	90,506
Liabilities:
Cash collateral for loaned securities	109,798	65,418
Short-term debt	373,000	423,000
Long-term debt	1,281,000	1,288,000
Fair Value
Assets:
Commercial mortgage and other loans	1,827,180	1,784,435
Policy loans	1,137,735	1,123,912
Other long-term investments	15,660	11,085
Cash and cash equivalents	154,501	147,109
Accrued investment income	93,591	90,506
Receivables from parent and affiliates	80,110	70,668
Other assets	28,384	24,126
Total assets	3,337,161	3,251,841
Liabilities:
Policyholders’ account balances - investment contracts	1,115,714	969,757
Cash collateral for loaned securities	109,798	65,418
Short-term debt	377,016	429,903
Long-term debt	1,311,375	1,321,501
Payables to parent and affiliates	55,039	53,027
Other liabilities	305,340	315,736
Total liabilities	3,274,282	3,155,342
Fair Value | Level 1
Assets:
Commercial mortgage and other loans	0	0
Policy loans	$ 0	0
Other long-term investments		0
Cash and cash equivalents	$ 51,278	53,476
Accrued investment income		0
Receivables from parent and affiliates		0
Other assets		0
Total assets	$ 51,278	53,476
Liabilities:
Policyholders’ account balances - investment contracts	$ 0	0
Cash collateral for loaned securities		0
Short-term debt		0
Long-term debt		0
Payables to parent and affiliates		0
Other liabilities		0
Total liabilities	$ 0	0
Fair Value | Level 2
Assets:
Commercial mortgage and other loans	8,448	8,486
Policy loans	$ 0	0
Other long-term investments		0
Cash and cash equivalents	$ 103,223	93,633
Accrued investment income	93,591	90,506
Receivables from parent and affiliates	80,110	70,668
Other assets	28,384	24,126
Total assets	313,756	287,419
Liabilities:
Policyholders’ account balances - investment contracts	885,644	929,694
Cash collateral for loaned securities	109,798	65,418
Short-term debt	377,016	429,903
Long-term debt	1,311,375	1,321,501
Payables to parent and affiliates	55,039	53,027
Other liabilities	305,340	315,736
Total liabilities	3,044,212	3,115,279
Fair Value | Level 3
Assets:
Commercial mortgage and other loans	1,818,732	1,775,949
Policy loans	1,137,735	1,123,912
Other long-term investments	15,660	11,085
Cash and cash equivalents	$ 0	0
Accrued investment income		0
Receivables from parent and affiliates		0
Other assets		0
Total assets	$ 2,972,127	2,910,946
Liabilities:
Policyholders’ account balances - investment contracts	$ 230,070	40,063
Cash collateral for loaned securities		0
Short-term debt		0
Long-term debt		0
Payables to parent and affiliates		0
Other liabilities		0
Total liabilities	$ 230,070	40,063
Carrying Amount
Assets:
Commercial mortgage and other loans	1,747,153	1,681,553
Policy loans	1,137,735	1,123,912
Other long-term investments	14,830	10,168
Cash and cash equivalents	154,501	147,109
Accrued investment income	93,591	90,506
Receivables from parent and affiliates	80,110	70,689
Other assets	28,384	24,126
Total assets	3,256,304	3,148,063
Liabilities:
Policyholders’ account balances - investment contracts	1,123,260	976,190
Cash collateral for loaned securities	109,798	65,418
Short-term debt	373,000	423,000
Long-term debt	1,281,000	1,288,000
Payables to parent and affiliates	55,039	53,027
Other liabilities	305,340	315,736
Total liabilities	$ 3,247,437	$ 3,121,371