. as of december 31 , 2013 , the company has provided $ 23 million of valuation allowance against certain of these deferred tax assets based on management's determination that it is more-likely-than-not that the tax benefits related to these assets will not be realized . the valuation allowance was reduced in 2013 mainly due to the expiration of the tax attributes . during 2013 , the company contributed $ 476 million to its u.s . and international pension plans and $ 6 million to its postretirement plans