Business Segments - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2011
Segment Reporting Disclosure [Line Items]
Gain (loss) on sale of aviation equipment, pretax	$ (979,000)	[1],[2]
Gain (Loss) on disposal of equipment, net of tax	(636,000)
Pretax estimated liability for state administrative settlement	6,000,000
After tax estimated liability for state administrative settlement	$ 3,900,000

[1] Loss on sale of equipment.

[2] The 2011 balances have been retroactively adjusted to give effect to the adoption of new accounting guidance as described in Note F-Adoption of New Accounting Standard.