Fair Value Measurements - Fair Values and Unrealized Losses on Securities Available-for-Sale (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months, Estimated fair value	$ 1,504	$ 15,683
Less than Twelve Months, Gross unrealized losses	1	19
Twelve Months or More, Estimated fair value	0	0
Twelve Months or More, Gross unrealized losses	0	0
Estimated fair value, Total	1,504	15,683
Gross unrealized losses, Total	(1)	(19)
Municipal Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months, Estimated fair value	1,504	4,955
Less than Twelve Months, Gross unrealized losses	1	6
Twelve Months or More, Estimated fair value	0	0
Twelve Months or More, Gross unrealized losses	0	0
Estimated fair value, Total	1,504	4,955
Gross unrealized losses, Total	(1)	(6)
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months, Estimated fair value		10,728
Less than Twelve Months, Gross unrealized losses		13
Twelve Months or More, Estimated fair value	0	0
Twelve Months or More, Gross unrealized losses	0	0
Estimated fair value, Total		10,728
Gross unrealized losses, Total		$ (13)