Note B - Recent Accounting Pronouncements (Details Textual) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Reclassification of Gain (Loss) Unrealized on Equity Securities from AOCI to Retained Earnings
AOCI Attributable to Parent [Member]
Reclassification of Gain (Loss) Unrealized on Equity Securities from AOCI to Retained Earnings	(7,444)
Retained Earnings [Member]
Reclassification of Gain (Loss) Unrealized on Equity Securities from AOCI to Retained Earnings	7,444
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member]
Reclassification of Gain (Loss) Unrealized on Equity Securities from AOCI to Retained Earnings	(7,400)
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Reclassification of Gain (Loss) Unrealized on Equity Securities from AOCI to Retained Earnings	$ 7,400