Loans (Analysis of Impaired Loans) (Details) - Loans, Excluding Purchased Credit Impaired Loans [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Modifications	Dec. 31, 2015 USD ($) Modifications	Dec. 31, 2014 USD ($) Modifications
Financing Receivable, Modifications, Number of Contracts | Modifications	54	7	8
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 6,042,304	$ 5,618,041
Recorded Investment of Loans Individually Measured for Specific Impairment	25,459	16,080
Recorded Investment	4,464	15
Unpaid Principal Balance	4,558	15
Related Allowance	57	15
Impaired Financing Receivable, Average Recorded Investment	21,493	22,372	$ 26,635
Impaired Financing Receivable, Interest Income, Accrual Method	$ 237	$ 202	$ 1,327
Commercial business: Secured loans [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	9	5	4
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 2,442,772	$ 2,257,168
Recorded Investment of Loans Individually Measured for Specific Impairment	8,818	5,524
Recorded Investment	2,414	690
Unpaid Principal Balance	2,484	718
Related Allowance	664	321
Impaired Financing Receivable, Average Recorded Investment	9,368	7,987	$ 7,345
Impaired Financing Receivable, Interest Income, Accrual Method	79	84	36
Commercial business: Unsecured loans [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	94,737	94,948
Recorded Investment of Loans Individually Measured for Specific Impairment	0	0
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Impaired Financing Receivable, Average Recorded Investment	0	0	19
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 0	$ 1
Real estate: One-to-four family residential [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	3	1	2
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 167,403	$ 172,150
Recorded Investment of Loans Individually Measured for Specific Impairment	529	1,286
Recorded Investment	435	314
Unpaid Principal Balance	693	339
Related Allowance	12	314
Impaired Financing Receivable, Average Recorded Investment	743	2,848	$ 2,094
Impaired Financing Receivable, Interest Income, Accrual Method	10	47	49
Real estate: Commercial and multifamily residential: Commercial land [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	270,106	213,158
Recorded Investment of Loans Individually Measured for Specific Impairment	708	0
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Impaired Financing Receivable, Average Recorded Investment	425	94	82
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 0	$ 0
Real estate: Commercial and multifamiIy residential: Income property [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	0	0	1
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 1,365,321	$ 1,308,673
Recorded Investment of Loans Individually Measured for Specific Impairment	4,425	2,106
Recorded Investment	540	0
Unpaid Principal Balance	544	0
Related Allowance	27	0
Impaired Financing Receivable, Average Recorded Investment	2,492	2,913	$ 6,782
Impaired Financing Receivable, Interest Income, Accrual Method	$ 26	$ 36	$ 270
Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	1	0	1
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 1,054,564	$ 940,261
Recorded Investment of Loans Individually Measured for Specific Impairment	5,414	6,055
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Impaired Financing Receivable, Average Recorded Investment	5,084	7,052	$ 9,472
Impaired Financing Receivable, Interest Income, Accrual Method	0	26	956
Real estate construction: One-to-four family residential: Land and acquisition [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	11,542	14,283
Recorded Investment of Loans Individually Measured for Specific Impairment	14	467
Recorded Investment	14	0
Unpaid Principal Balance	102	0
Related Allowance	1	0
Impaired Financing Receivable, Average Recorded Investment	199	641	694
Impaired Financing Receivable, Interest Income, Accrual Method	0	5	6
Real estate construction: One-to-four family residential: Residential construction [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	109,293	119,813
Recorded Investment of Loans Individually Measured for Specific Impairment	336	562
Recorded Investment	0	335
Unpaid Principal Balance	0	335
Related Allowance	0	3
Impaired Financing Receivable, Average Recorded Investment	472	648	0
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	$ 0
Real estate construction: Commercial and multifamily residential: Income property [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	103,779	83,634
Recorded Investment of Loans Individually Measured for Specific Impairment	0	0
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Real estate construction: Commercial and multifamily residential: Owner occupied [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	103,480	81,671
Recorded Investment of Loans Individually Measured for Specific Impairment	0	0
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	$ 0	$ 0
Consumer [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	41	1	0
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 319,307	$ 332,282
Recorded Investment of Loans Individually Measured for Specific Impairment	5,215	80
Impaired Financing Receivable, Average Recorded Investment	2,710	189	$ 147
Impaired Financing Receivable, Interest Income, Accrual Method	122	4	$ 9
Impaired Loans Without Recorded Allowance [Member]
Recorded Investment	17,592	14,726
Unpaid Principal Balance	27,228	19,547
Impaired Loans With Recorded Allowance [Member]
Recorded Investment	7,867	1,354
Unpaid Principal Balance	8,381	1,407
Related Allowance	761	653
Impaired Loans Without Recorded Allowance [Member]
Recorded Investment	751	65
Unpaid Principal Balance	833	139
Impaired Loans Without Recorded Allowance [Member] | Commercial business: Secured loans [Member]
Recorded Investment	6,404	4,834
Unpaid Principal Balance	12,831	6,455
Impaired Loans Without Recorded Allowance [Member] | Commercial business: Unsecured loans [Member]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Impaired Loans Without Recorded Allowance [Member] | Real estate: One-to-four family residential [Member]
Recorded Investment	94	972
Unpaid Principal Balance	291	1,397
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]
Recorded Investment	708	0
Unpaid Principal Balance	687	0
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]
Recorded Investment	3,885	2,106
Unpaid Principal Balance	4,148	2,311
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Recorded Investment	5,414	6,055
Unpaid Principal Balance	8,102	8,528
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]
Recorded Investment	0	467
Unpaid Principal Balance	0	490
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]
Recorded Investment	336	227
Unpaid Principal Balance	336	227
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]
Recorded Investment	0	0
Unpaid Principal Balance	$ 0	$ 0