Available-For-Sale Securities Adjusted cost (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	$ 55,088,000	$ 66,514,000
Unrealized Gains	690,000	1,442,000
Unrealized Losses	(217,000)	(263,000)
Accrued Interest	67,000	109,000
Estimated Fair Value	55,628,000	67,802,000
Cash & Cash Equivalents	27,631,000	36,382,000	47,980,000	39,937,000
Investment Securities	27,997,000	31,420,000
Cash
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	27,177,000	30,958,000
Unrealized Gains	0	0
Unrealized Losses	0	0
Accrued Interest	0	0
Estimated Fair Value	27,177,000	30,958,000
Cash & Cash Equivalents	27,177,000	30,958,000
Investment Securities	0	0
Fair Value, Inputs, Level 1
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	19,436,000	24,037,000
Unrealized Gains	572,000	1,265,000
Unrealized Losses	(194,000)	(216,000)
Accrued Interest	13,000	26,000
Estimated Fair Value	19,827,000	25,112,000
Cash & Cash Equivalents	454,000	5,424,000
Investment Securities	19,373,000	19,688,000
Fair Value, Inputs, Level 1 | Money Market Accounts
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	454,000	5,424,000
Unrealized Gains	0	0
Unrealized Losses	0	0
Accrued Interest	0	0
Estimated Fair Value	454,000	5,424,000
Cash & Cash Equivalents	454,000	5,424,000
Investment Securities	0	0
Fair Value, Inputs, Level 1 | Mutual Funds
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	11,688,000	7,887,000
Unrealized Gains	68,000	127,000
Unrealized Losses	(124,000)	(164,000)
Accrued Interest	0	0
Estimated Fair Value	11,632,000	7,850,000
Cash & Cash Equivalents	0	0
Investment Securities	11,632,000	7,850,000
Fair Value, Inputs, Level 1 | Corporate Equity Securities
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	2,736,000	4,614,000
Unrealized Gains	472,000	1,076,000
Unrealized Losses	(57,000)	(9,000)
Accrued Interest	0	0
Estimated Fair Value	3,151,000	5,681,000
Cash & Cash Equivalents	0	0
Investment Securities	3,151,000	5,681,000
Fair Value, Inputs, Level 1 | Government Agency Securities
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	4,558,000	6,112,000
Unrealized Gains	32,000	62,000
Unrealized Losses	(13,000)	(43,000)
Accrued Interest	13,000	26,000
Estimated Fair Value	4,590,000	6,157,000
Cash & Cash Equivalents	0	0
Investment Securities	4,590,000	6,157,000
Fair Value, Inputs, Level 2
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	8,475,000	11,519,000
Unrealized Gains	118,000	177,000
Unrealized Losses	(23,000)	(47,000)
Accrued Interest	54,000	83,000
Estimated Fair Value	8,624,000	11,732,000
Cash & Cash Equivalents	0	0
Investment Securities	8,624,000	11,732,000
Fair Value, Inputs, Level 2 | Municipal Bonds
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	3,657,000	3,524,000
Unrealized Gains	94,000	103,000
Unrealized Losses	(7,000)	0
Accrued Interest	24,000	25,000
Estimated Fair Value	3,768,000	3,652,000
Cash & Cash Equivalents	0	0
Investment Securities	3,768,000	3,652,000
Fair Value, Inputs, Level 2 | Corporate Bonds
Cash and Cash Equivalents and Marketable Securities [Line Items]
Cost	4,818,000	7,995,000
Unrealized Gains	24,000	74,000
Unrealized Losses	(16,000)	(47,000)
Accrued Interest	30,000	58,000
Estimated Fair Value	4,856,000	8,080,000
Cash & Cash Equivalents	0	0
Investment Securities	$ 4,856,000	$ 8,080,000