BOK Financial's (BOKF) portfolio of outstanding loans decreased by $13 million in the first quarter. The bank holding company reported Tuesday first-quarter income of $64.8 million, or 94 cents a share, for the three months ended March 31, up from $60.3 million, or 88 cents a share, one year earlier. Although, the amount of bad commercial real estate loans held by BOK Financial is nearly triple the number of nonperforming residential mortgages on its books. The company boasted a higher credit quality portfolio in the first quarter, as total nonperforming assets fell 21.5% to about $379.1 million from $483 million a year earlier. About $37.8 million residential mortgages were nonperforming in the first quarter, along with $125.5 million in commercial real estate, the firm reported. Provisions for credit losses totaled $6.3 million during the period, down more than 85% from the first quarter of 2010. The Tulsa, Okla.-based company also increased its quarterly cash dividend, citing the strong quarterly results. "The company's performance and capital position allows us to increase our quarterly cash dividend," said Stan Lybarger, president and chief executive of BOK Financial. "This is the sixth consecutive annual increase since we paid our first cash dividend in the second quarter of 2005. Outstanding commercial loan balances were up in most of our markets and net interest revenue increased over the previous quarter. We continue to see steady credit quality improvements." Net interest revenue for the first quarter rose 17% to $164.4 million from nearly $140.5 million a year earlier. Interest revenue rose by $7 million from the fourth quarter. The average balance of the company's securities portfolio fell $319 million during the first quarter, including a $239 million decrease in securities available for sale and a $78 million drop in mortgage trading securities held as an economic hedge of mortgage servicing rights. The company said REO and other repossessed assets decreased by $10 million during the first quarter because additions of $21 million partially offset $15 million in sales and $4.3 million in write-downs and losses. Construction and land development commercial real estate loans fell by $54 million in the first quarter of 2011, as residential mortgage loans decreased $51 million and consumer loans declines $62 million. As of March 31, BOK Financial had total assets of $23.7 billion. Write to Christine Ricciardi. Follow her on Twitter @HWnewbieCR.