Loans Receivable and The Allowance For Loan Losses: Schedule of Accounts, Notes, Loans and Financing Receivable (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011		Jun. 30, 2011
Consumer
Loans Receivable Amount	$ 103,504		$ 103,347		$ 97,396
Loans Receivable Percent of Total	3.20%		3.10%		2.90%
Consumer secured by one- to four-family
Loans Receivable Amount	173,731		181,049		182,778
Loans Receivable Percent of Total	5.40%		5.50%		5.50%
Total consumer
Loans Receivable Amount	277,235		284,396		280,174
Loans Receivable Percent of Total	8.60%		8.60%		8.40%
Total loans outstanding
Loans Receivable Amount	3,212,257		3,296,338		3,306,667
Loans Receivable Percent of Total	100.00%		100.00%		100.00%
Less allowance for loan losses
Loans Receivable Amount	(80,221)		(82,912)		(92,000)
Net loans
Loans Receivable Amount	3,132,036		3,213,426		3,214,667
Commercial real estate owner occupied
Loans Receivable Amount	477,621		469,806		507,751
Loans Receivable Percent of Total	14.90%		14.20%		15.30%
Commercial real estate investment properties
Loans Receivable Amount	613,965		621,622		582,569
Loans Receivable Percent of Total	19.10%		18.90%		17.60%
Multifamily real estate
Loans Receivable Amount	130,319		139,710		147,951
Loans Receivable Percent of Total	4.10%		4.20%		4.50%
Commercial construction
Loans Receivable Amount	23,808		42,391		35,790
Loans Receivable Percent of Total	0.70%		1.30%		1.10%
Multifamily construction
Loans Receivable Amount	18,132		19,436		20,552
Loans Receivable Percent of Total	0.60%		0.60%		0.60%
One- to four-family construction
Loans Receivable Amount	157,301		144,177		140,669
Loans Receivable Percent of Total	4.80%		4.40%		4.40%
Land development residential
Loans Receivable Amount	83,185		97,491		128,920
Loans Receivable Percent of Total	2.60%		3.00%		3.90%
Land development commercial
Loans Receivable Amount	11,451		15,197		29,347
Loans Receivable Percent of Total	0.40%		0.50%		0.90%
Commercial business
Loans Receivable Amount	600,046		601,440		566,243
Loans Receivable Percent of Total	18.70%		18.20%		17.10%
Agricultural business
Loans Receivable Amount	211,705	[1]	218,171	[1]	208,485	[1]
Loans Receivable Percent of Total	6.60%	[1]	6.60%	[1]	6.30%	[1]
One- to four-family real estate
Loans Receivable Amount	$ 607,489		$ 642,501		$ 658,216
Loans Receivable Percent of Total	18.90%		19.50%		19.90%

[1] Including secured by farmland.