Columbia Bank has officially expanded into Idaho.

The Tacoma-based regional banking system announced that, as of Saturday, its acquisition of Sandpoint-based Intermountain Bancorp - parent company of Panhandle State Bank - was complete.

Panhandle State Bank was immediately merged into Columbia State Bank.

There are now 16 Columbia State Bank locations in Idaho, including the former Panhandle State Bank branches in Coeur d'Alene, Post Falls and Rathdrum.

With this transaction, Columbia's total assets are approximately $8.5 billion, with more than 150 branches throughout Washington, Oregon and Idaho.

Columbia also appointed Ford Elsaesser, the former chairman of Intermountain, to serve on Columbia's Board and the Board of Columbia State Bank.

"We are delighted to welcome the customers, employees, and shareholders of Intermountain to Columbia," said Melanie J. Dressel, president and chief executive officer of Columbia. "This acquisition marks our entry into the Idaho market and furthers our long stated objective of being the leading Pacific Northwest regional community bank.

"The complementary aspects of the companies' businesses, including customer focus, business orientation and compatibility of values and operating styles, make the merger a natural fit."

Columbia will separately announce, when the information is available, the final results of the merger consideration elected to be received by former Intermountain shareholders.