Consideration Transferred, Identifiable Net Assets Acquired and Goodwill Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Liabilities assumed
Goodwill recognized	$ 6,415	$ 10,932	$ 0
Treasure State Bank
Fair value of consideration transferred
Fair value of Company shares issued, net of equity issuance costs	10,465
Cash consideration for outstanding shares	3,475
Contingent consideration	0
Total fair value of consideration transferred	13,940
Identifiable assets acquired
Cash and cash equivalents	10,176
Investment securities	0
Loans receivable	51,875
Core deposit intangible	762
Accrued income and other assets	6,937
Total identifiable assets acquired	69,750
Liabilities assumed
Deposits	58,364
FHLB advances and repurchase agreements	3,260
Accrued expenses and other liabilities	601
Total liabilities assumed	62,225
Total identifiable net assets	7,525
Goodwill recognized	$ 6,415
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
Canon National Bank
Fair value of consideration transferred
Fair value of Company shares issued, net of equity issuance costs		15,163
Cash consideration for outstanding shares		16,145
Contingent consideration		0
Total fair value of consideration transferred		31,308
Identifiable assets acquired
Cash and cash equivalents		17,860
Investment securities		68,486
Loans receivable		159,759
Core deposit intangible		4,532
Accrued income and other assets		9,689
Total identifiable assets acquired		260,326
Liabilities assumed
Deposits		237,326
FHLB advances and repurchase agreements		0
Accrued expenses and other liabilities		1,487
Total liabilities assumed		238,813
Total identifiable net assets		21,513
Goodwill recognized		$ 9,795
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years
Montana Community Banks, Inc.
Fair value of consideration transferred
Fair value of Company shares issued, net of equity issuance costs		$ 10,776
Cash consideration for outstanding shares		12,219
Contingent consideration		0
Total fair value of consideration transferred		22,995
Identifiable assets acquired
Cash and cash equivalents		31,931
Investment securities		42,350
Loans receivable		84,689
Core deposit intangible		2,087
Accrued income and other assets		13,580
Total identifiable assets acquired		174,637
Liabilities assumed
Deposits		146,820
FHLB advances and repurchase agreements		3,292
Accrued expenses and other liabilities		2,667
Total liabilities assumed		152,779
Total identifiable net assets		21,858
Goodwill recognized		$ 1,137
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years