XML 102 R87.htm IDEA: XBRL DOCUMENT v3.8.0.1
Deferred Policy Acquisition Costs, Deferred Sales Inducements and Lifetime Income Benefit Rider Reserves (Narrative) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Insurance [Abstract]        
Deferred policy acquisition costs, increase (decrease) in amortization due to unlocking adjustment $ (48,200) $ 48,200 $ (11,000)  
Deferred sales inducements, increase (decrease) in amortization due to unlocking adjustment (34,300) 35,800 (5,600)  
Reserves for lifetime income benefit riders, increase (decrease) due to unlocking adjustment 21,600 42,000 $ 18,300  
Lifetime income benefit rider, primary election age     70 years 67 years
Liability for Future Policy Benefit, by Product Segment [Line Items]        
Reserve held for lifetime income benefit riders 56,142,673 51,637,026    
Lifetime Income Benefit Rider [Member]        
Liability for Future Policy Benefit, by Product Segment [Line Items]        
Reserve held for lifetime income benefit riders $ 704,400 $ 533,400