Summary of stock option activity (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Options Outstanding
Outstanding at beginning of period			100,437	160,986	160,986
Granted			0		0
Exercised	0	0	0	0	0
Forfeited			0		0
Expired			(55,640)		(60,549)
Outstanding at end of period	44,797		44,797		100,437
Share Based Compensation Arrangement By Share Based Payment Award Options Additional Disclosures Abstract
Outstanding at beginning of period			$ 253.64	$ 222.71	$ 222.71
Granted			$ 0		$ 0
Exercised			$ 0		$ 0
Forfeited			$ 0		$ 0
Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price			$ 238.85		$ 171.42
Outstanding at end of period	$ 272.00		$ 272.00		$ 253.64