Mergers and Acquisitions Consideration Transferred, Identifiable Net Assets Acquired and Goodwill Recognized (Details) - USD ($)				3 Months Ended		9 Months Ended
		Jul. 31, 2019	Apr. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Liabilities assumed
Goodwill recognized				$ 125,535,000	$ 0	$ 166,836,000	$ 111,724,000
Heritage Bank
Fair value of consideration transferred
Fair value of Company shares issued		$ 229,385,000
Cash consideration		16,420,000
Total fair value of consideration transferred		245,805,000
Identifiable assets acquired
Cash and cash equivalents		84,446,000
Debt securities		103,231,000
Loans receivable		615,279,000
Core deposit intangible		13,566,000
Accrued income and other assets		35,891,000
Total identifiable assets acquired		852,413,000
Liabilities assumed
Deposits		722,220,000
Borrowings		0
Accrued expenses and other liabilities		9,923,000
Total liabilities assumed		732,143,000
Total identifiable net assets		120,270,000
Goodwill recognized		$ 125,535,000
Core Deposit Intangible, Weighted Average Useful Life		10 years
First Community Bank Utah
Fair value of consideration transferred
Fair value of Company shares issued			$ 87,153,000
Cash consideration			4,000
Total fair value of consideration transferred			87,157,000
Identifiable assets acquired
Cash and cash equivalents			11,311,000
Debt securities			47,247,000
Loans receivable			245,485,000
Core deposit intangible	[1]		8,963,000
Accrued income and other assets			24,848,000
Total identifiable assets acquired			337,854,000
Liabilities assumed
Deposits			274,646,000
Borrowings	[2]		7,273,000
Accrued expenses and other liabilities			10,079,000
Total liabilities assumed			291,998,000
Total identifiable net assets			45,856,000
Goodwill recognized			$ 41,301,000
Core Deposit Intangible, Weighted Average Useful Life			10 years
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Subordinated Debentures			$ 5,864,000

[1] The core deposit intangible for each acquisition was determined to have an estimated life of 10 years.

[2] Borrowings assumed with the FNB acquisition include Tier 1 subordinated debentures of $5,864,000.