XML 55 R42.htm IDEA: XBRL DOCUMENT v3.8.0.1
Marketable Securities with Contractual Maturities (Detail) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost up to one year $ 1,167,187 $ 1,078,521
Gross unrealized gains up to one year 63 426
Gross unrealized losses up to one year (1,984) (507)
Fair value up to one year 1,165,266 1,078,440
Amortized cost, over one year through five years 2,456,715 2,308,920
Gross unrealized gains, over one year through five years 518 2,255
Gross unrealized losses, over one year through five years (19,918) (15,078)
Fair value, over one year through five years 2,437,315 2,296,097
Government And Corporate Debentures Fixed Interest Rate    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost up to one year 1,026,555 915,302
Gross unrealized gains up to one year 48 311
Gross unrealized losses up to one year (1,698) (446)
Fair value up to one year 1,024,905 915,167
Amortized cost, over one year through five years 1,985,849 1,770,641
Gross unrealized gains, over one year through five years 384 1,903
Gross unrealized losses, over one year through five years (15,204) (11,024)
Fair value, over one year through five years 1,971,029 1,761,520
Government Sponsored Enterprises    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost up to one year 112,951 149,972
Gross unrealized gains up to one year 1 99
Gross unrealized losses up to one year (275) (61)
Fair value up to one year 112,677 150,010
Amortized cost, over one year through five years 424,619 520,669
Gross unrealized gains, over one year through five years   282
Gross unrealized losses, over one year through five years (4,687) (4,052)
Fair value, over one year through five years 419,932 516,899
Government And Corporate Debentures Floating Interest Rate    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost up to one year 27,681 13,247
Gross unrealized gains up to one year 14 16
Gross unrealized losses up to one year (11)  
Fair value up to one year 27,684 13,263
Amortized cost, over one year through five years 46,247 17,610
Gross unrealized gains, over one year through five years 134 70
Gross unrealized losses, over one year through five years (27) (2)
Fair value, over one year through five years $ 46,354 $ 17,678