Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Narrative) (Loans) (Detail)	12 Months Ended
	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Minimum Number Of Days To Be Considered Past Due	90 days
Financing Receivable, 90 Days Past Due and Still Accruing	90 days
Threshold Period Past Due for Write-off of Financing Receivable (in days)	180 days
Minimum Period Troubled Debt Restructurings Placed On Non Accrual Status (in months)	6 months
Minimum Performance Period for TDR to return to Accrual Status (in months)	6 months
Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Minimum Number Of Days To Be Considered Past Due	90 days
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Minimum Number Of Days To Be Considered Past Due	90 days
Other Real Estate Owned [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Threshold Period Past Due for Write-off of Financing Receivable (in days)	90 days