Business Combinations Business Combinations	3 Months Ended
Mar. 31, 2019
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	BUSINESS COMBINATIONS There were no business combinations completed in the first quarter of 2019. 2018 Business Combinations Falls Water On September 13, 2018, NWN Water, then a wholly-owned subsidiary of NW Natural and now a wholly-owned subsidiary of NW Holdings, completed the acquisition of Falls Water Co., Inc. (Falls Water), a privately-owned water utility in the Pacific Northwest for preliminary non-cash consideration of $8.5 million, subject to closing adjustments, in the form of 125,000 shares of NW Natural common stock. Falls Water became a wholly-owned subsidiary of NWN Water and marked its first acquisition in the water utility sector. This acquisition aligns with NW Holdings' water sector strategy as the acquisition provides NWN Water entry into Idaho, expands service area, and opens further opportunity for growth. Falls Water is based in Idaho Falls, Idaho and serves approximately 5,300 connections. Through the purchase of all of the outstanding shares of Falls Water, NWN Water acquired the net assets and 100% control of Falls Water. We determined that the Falls Water acquisition met the criteria of a business combination, and as such performed a preliminary allocation of the consideration to the acquired assets and assumed liabilities based on their fair value as of the acquisition date, the majority of which was allocated to goodwill. The allocation is considered preliminary as of December 31, 2018, and is primarily associated with certain tax positions and goodwill. Subsequent adjustments are not expected to be significant, and any such adjustments are expected to be completed within a one-year measurement period. The acquisition costs were insignificant and were expensed as incurred. The results of Falls Water are not material to the consolidated financial results of NW Holdings. Preliminary goodwill of $6.4 million was recognized from this acquisition and is attributable to Falls Water's regulated service territory and experienced workforce as well as the strategic benefits expected from this high-growth service territory. NW Holdings has included this goodwill in other for segment reporting purposes, and it is not deductible for income tax purposes. No intangible assets aside from goodwill were acquired. Other Acquisitions During 2018, in addition to the Falls Water acquisition, NWN Water completed three acquisitions qualifying as business combinations. The aggregate fair value of the preliminary consideration transferred for these acquisitions was approximately $2.8 million. These business combinations, both individually and in aggregate, were not significant to NW Holdings' results of operations. Goodwill We allocate goodwill to reporting units based on the expected benefit from the business combination. We perform an annual impairment assessment of goodwill at the reporting unit level, or more frequently if events and circumstances indicate that goodwill might be impaired. An impairment loss is recognized if the carrying value of a reporting unit’s goodwill exceeds its fair value. As a result of all acquisitions completed in 2018, total goodwill was $9.0 million as of March 31, 2019 and December 31, 2018. The annual impairment assessment of goodwill occurs in the fourth quarter of each year. There have been no impairments recognized to date.

BUSINESS COMBINATIONS

There were no business combinations completed in the first quarter of 2019.

2018 Business Combinations

Falls Water

On September 13, 2018, NWN Water, then a wholly-owned subsidiary of NW Natural and now a wholly-owned subsidiary of NW Holdings, completed the acquisition of Falls Water Co., Inc. (Falls Water), a privately-owned water utility in the Pacific Northwest for preliminary non-cash consideration of $8.5 million, subject to closing adjustments, in the form of 125,000 shares of NW Natural common stock. Falls Water became a wholly-owned subsidiary of NWN Water and marked its first acquisition in the water utility sector. This acquisition aligns with NW Holdings' water sector strategy as the acquisition provides NWN Water entry into Idaho, expands service area, and opens further opportunity for growth. Falls Water is based in Idaho Falls, Idaho and serves approximately 5,300 connections.

Through the purchase of all of the outstanding shares of Falls Water, NWN Water acquired the net assets and 100% control of Falls Water. We determined that the Falls Water acquisition met the criteria of a business combination, and as such performed a preliminary allocation of the consideration to the acquired assets and assumed liabilities based on their fair value as of the acquisition date, the majority of which was allocated to goodwill. The allocation is considered preliminary as of December 31, 2018, and is primarily associated with certain tax positions and goodwill. Subsequent adjustments are not expected to be significant, and any such adjustments are expected to be completed within a one-year measurement period. The acquisition costs were insignificant and were expensed as incurred. The results of Falls Water are not material to the consolidated financial results of NW Holdings.

Preliminary goodwill of $6.4 million was recognized from this acquisition and is attributable to Falls Water's regulated service territory and experienced workforce as well as the strategic benefits expected from this high-growth service territory. NW Holdings has included this goodwill in other for segment reporting purposes, and it is not deductible for income tax purposes. No intangible assets aside from goodwill were acquired.

Other Acquisitions

During 2018, in addition to the Falls Water acquisition, NWN Water completed three acquisitions qualifying as business combinations. The aggregate fair value of the preliminary consideration transferred for these acquisitions was approximately $2.8 million. These business combinations, both individually and in aggregate, were not significant to NW Holdings' results of operations.

Goodwill

We allocate goodwill to reporting units based on the expected benefit from the business combination. We perform an annual impairment assessment of goodwill at the reporting unit level, or more frequently if events and circumstances indicate that goodwill might be impaired. An impairment loss is recognized if the carrying value of a reporting unit’s goodwill exceeds its fair value.

As a result of all acquisitions completed in 2018, total goodwill was $9.0 million as of March 31, 2019 and December 31, 2018. The annual impairment assessment of goodwill occurs in the fourth quarter of each year. There have been no impairments recognized to date.