XML 44 R33.htm IDEA: XBRL DOCUMENT v3.8.0.1
Fair Value of Financial Instruments Fair Value of Financial Instruments, Reconciliation of Level 3 Securities (Details) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Beginning balance, January 1 $ 2,552,600  
Transfers (out) of Level 3 (1) (7,000) [1] $ 0
Purchases and sales, net (200) 4,900
Ending balance, September 30 2,624,800  
Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Beginning balance, January 1 11,900 0
Ending balance, September 30 $ 4,700 $ 4,900
[1] (1)Transferred from Level 3 to Level 2 because observable market data became available for the securities.