Investments (Gross Unrealized Losses and Fair Value by Length of Time of Available-For-Sale Securities) (Detail) $ in Thousands	Sep. 30, 2015 USD ($) Securities	Dec. 31, 2014 USD ($) Securities
Schedule Of Available For Sale Securities [Line Items]
Fair Value	$ 121,398	$ 253,226
Less than 12 months	33	122
More than 12 months	1,102	5,748
Total Unrealized Losses	$ 1,135	$ 5,870
Available-for-Sale Securities
Schedule Of Available For Sale Securities [Line Items]
Number of securities | Securities	21	37
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Fair Value	$ 39,871	$ 141,679
Less than 12 months	17	60
More than 12 months	89	2,758
Total Unrealized Losses	$ 106	$ 2,818
U.S. Government Agencies | Available-for-Sale Securities
Schedule Of Available For Sale Securities [Line Items]
Number of securities | Securities	3	14
State and municipal
Schedule Of Available For Sale Securities [Line Items]
Fair Value		$ 1,409
Less than 12 months		4
More than 12 months		0
Total Unrealized Losses		$ 4
State and municipal | Available-for-Sale Securities
Schedule Of Available For Sale Securities [Line Items]
Number of securities | Securities		2
Mortgage-Backed
Schedule Of Available For Sale Securities [Line Items]
Fair Value	$ 80,532	$ 108,902
Less than 12 months	16	58
More than 12 months	930	2,878
Total Unrealized Losses	$ 946	$ 2,936
Mortgage-Backed | Available-for-Sale Securities
Schedule Of Available For Sale Securities [Line Items]
Number of securities | Securities	17	20
Trust Preferred
Schedule Of Available For Sale Securities [Line Items]
Fair Value	$ 995	$ 1,236
Less than 12 months	0	0
More than 12 months	83	112
Total Unrealized Losses	$ 83	$ 112
Trust Preferred | Available-for-Sale Securities
Schedule Of Available For Sale Securities [Line Items]
Number of securities | Securities	1	1