Fair Value of Assets and Liabilities (Financial Instruments where Carrying Amounts and Fair Values May Differ) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Assets:
Policy loans	$ 1,153,528	$ 1,143,303
Accrued investment income	81,079	100,031
Liabilities:
Cash collateral for loaned securities	156,688	40,416
Short-term debt	0	180,000
Long-term debt	0	1,204,000
Fair Value
Assets:
Commercial mortgage and other loans	1,088,880	1,710,491
Policy loans	1,153,528	1,143,303
Short-term investments	5,000
Cash and cash equivalents	132,552	175,361
Accrued investment income	81,079	100,031
Receivables from parent and affiliates	82,157	65,628
Other assets	28,108	6,162
Total assets	2,571,304	3,200,976
Liabilities:
Policyholders’ account balances - investment contracts	1,269,220	1,184,744
Cash collateral for loaned securities	156,688	40,416
Short-term debt		180,105
Long-term debt		1,227,110
Payables to parent and affiliates	55,568	72,791
Other liabilities	252,619	343,089
Total liabilities	1,734,095	3,048,255
Fair Value | Accounting Standards Update 2015-07
Liabilities:
Cost Method Investments, Fair Value Disclosure	32,000	27,000
Fair Value | Level 1
Assets:
Commercial mortgage and other loans	0	0
Policy loans	0	0
Short-term investments	0
Cash and cash equivalents	26,552	19,297
Accrued investment income	0	0
Receivables from parent and affiliates	0	0
Other assets	0	0
Total assets	26,552	19,297
Liabilities:
Policyholders’ account balances - investment contracts	0	0
Cash collateral for loaned securities	0	0
Short-term debt		0
Long-term debt		0
Payables to parent and affiliates	0	0
Other liabilities	0	0
Total liabilities	0	0
Fair Value | Level 2
Assets:
Commercial mortgage and other loans	0	8,540
Policy loans	0	0
Short-term investments	5,000
Cash and cash equivalents	106,000	156,064
Accrued investment income	81,079	100,031
Receivables from parent and affiliates	82,157	65,628
Other assets	28,108	6,162
Total assets	302,344	336,425
Liabilities:
Policyholders’ account balances - investment contracts	1,019,421	947,853
Cash collateral for loaned securities	156,688	40,416
Short-term debt		180,105
Long-term debt		1,227,110
Payables to parent and affiliates	55,568	72,791
Other liabilities	252,619	343,089
Total liabilities	1,484,296	2,811,364
Fair Value | Level 3
Assets:
Commercial mortgage and other loans	1,088,880	1,701,951
Policy loans	1,153,528	1,143,303
Short-term investments	0
Cash and cash equivalents	0	0
Accrued investment income	0	0
Receivables from parent and affiliates	0	0
Other assets	0	0
Total assets	2,242,408	2,845,254
Liabilities:
Policyholders’ account balances - investment contracts	249,799	236,891
Cash collateral for loaned securities	0	0
Short-term debt		0
Long-term debt		0
Payables to parent and affiliates	0	0
Other liabilities	0	0
Total liabilities	249,799	236,891
Carrying Amount
Assets:
Commercial mortgage and other loans	1,023,427	1,658,235
Policy loans	1,153,528	1,143,303
Short-term investments	5,000
Cash and cash equivalents	132,552	175,361
Accrued investment income	81,079	100,031
Receivables from parent and affiliates	82,157	65,628
Other assets	28,108	6,162
Total assets	2,505,851	3,148,720
Liabilities:
Policyholders’ account balances - investment contracts	1,270,490	1,190,596
Cash collateral for loaned securities	156,688	40,416
Short-term debt		180,000
Long-term debt		1,204,000
Payables to parent and affiliates	55,568	72,791
Other liabilities	252,619	343,089
Total liabilities	1,735,365	3,030,892
Carrying Amount | Accounting Standards Update 2015-07
Liabilities:
Cost Method Investments, Fair Value Disclosure	$ 30,000	$ 26,000