Despite a seemingly ever widening basis swap dramatically increasing the cost of offshore bond issuance, the major banks ramped up their offshore issuance last week. Westpac, National Australia and Commonwealth banks issued the equivalent of A$8.8 billion of bonds in international markets. Westpac started the week issuing US$2.0 billion of three-year bonds and US$2.0 billion of ten-year bonds in the US s144A market. The bonds priced at 100 basis points and 155 bps over US Treasuries, respectively.NAB raised €2.0 billion in the Euromarket for just over five years at 83 bps over mid swaps. This works out at about 130 bps over swap after allowing for the euro-Australian dollar basis swap. And CBA paid mid-swaps plus 25 bps for US$1.25 billion, for five years, in the US s144A market with a government guarantee.  This works out about the same as what nab paid after allowing for the US dollar-Australian dollar basis swap.The chart below shows what has happened to the US dollar-Australian dollar basis swap in recent weeks. The picture is much the same for euro-Australian dollar basis swaps.  As can be seen, the basis swap has been pushed out to wider than normal levels by the massive offshore issuance, principally from the banks, since the start of the year but in recent weeks it has moved dramatically higher. At what point will this become too expensive?It seems the cost of Australia's offshore debt binge is not going to be reflected in the exchange rate but in the cost to hedge the foreign exchange risk.The three major banks were not the only offshore borrowers last week. Suncorp Metway quietly raised US$250 million for 18 months in the Euromarket. The government-guaranteed issue priced at Libor plus 16 bps.Amcor Limited announced the pricing of a US$850 million debt raising in the traditional private placement or Reg D market, in the US. Amcor raised US$275 million for seven years, US$300 million for nine years and US$275 million for twelve years. And the Australian branch of Rabobank opened a new January 2013 line in the Euromarket, raising A$200 million. The Australian dollar denominated issue will have no impact on the basis swap.Finally, Toyota Australia Finance has registered two Uridashi bonds to be issued on December 16. No details have been disclosed on the size or pricing of the two- and three-year bonds.