Policyholders' Liabilities (Future Policy Benefits) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Liability for Future Policy Benefit, by Product Segment [Line Items]
Individual and group annuities and supplementary contracts	$ 548,064	$ 519,462
Other contract liabilities	5,071,616	5,238,061
Total future policy benefits	16,503,260	15,198,755
Domestic
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life insurance	9,643,227	8,277,233
Taiwan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life insurance	$ 1,240,353	$ 1,163,999