Note 9 - Net Income Per Share of Class A and Class B Common Stock (Detail) - Earnings Per Share Reconciliation (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Numerator:
Income from continuing operations applicable to common stockholders	$ 79,395	$ 55,210	$ 13,587
Denominator:
Weighted average number of shares outstanding used to calculate basic income per share (in Shares)	25,696	26,230	26,062
Weighted average number of shares outstanding used to calculate diluted income per share (in Shares)	26,170	26,664	26,279
Basic income from continuing operations per share applicable to common stockholders (in Dollars per share)	$ 3.09	$ 2.10	$ 0.52
Diluted income from continuing operations per share available to common stockholders (in Dollars per share)	$ 3.03	$ 2.07	$ 0.52
Basic [Member] | Common Class A [Member]
Numerator:
Distributed income applicable to common stockholders	(10,497)	(5,844)	(3,353)
Numerator:
Distributed income applicable to common stockholders	10,497	5,844	3,353
Basic [Member] | Common Class B [Member]
Numerator:
Distributed income applicable to common stockholders	(1,569)	(978)	(566)
Numerator:
Distributed income applicable to common stockholders	1,569	978	566
Distributed [Member] | Common Class A [Member]
Numerator:
Reallocation of income as a result of conversion of dilutive stock options	28	15	5
Reallocation of income due to conversion of Class B to Class A	1,541	963	561
Distributed [Member] | Common Class B [Member]
Numerator:
Reallocation of income as a result of conversion of dilutive stock options	(28)	(15)	(5)
Diluted [Member] | Common Class A [Member]
Numerator:
Distributed income applicable to common stockholders	(12,066)	(6,822)	(3,919)
Numerator:
Distributed income applicable to common stockholders	12,066	6,822	3,919
Diluted [Member] | Common Class B [Member]
Numerator:
Distributed income applicable to common stockholders	(1,541)	(963)	(561)
Numerator:
Distributed income applicable to common stockholders	1,541	963	561
Undistributed [Member] | Common Class A [Member]
Numerator:
Reallocation of income as a result of conversion of dilutive stock options	159	113	11
Reallocation of income due to conversion of Class B to Class A	8,598	6,827	1,384
Undistributed [Member] | Common Class B [Member]
Numerator:
Reallocation of income as a result of conversion of dilutive stock options	(159)	(113)	(11)
Stock Options [Member] | Common Class A [Member]
Antidilutive Securities:
Shares issuable pursuant to stock options not included since they were antidilutive (in Shares)	45	280	661
Common Class A [Member]
Numerator:
Income from continuing operations applicable to common stockholders	69,069	47,292	11,626
Undistributed income from continuing operations applicable to common stockholders	58,572	41,448	8,273
Denominator:
Weighted average number of shares outstanding used to calculate basic income per share (in Shares)	22,354	22,468	22,300
Weighted average number of shares from stock options (in Shares)	474	434	217
Conversion of Class B to Class A (in Shares)	3,342	3,762	3,762
Weighted average number of shares outstanding used to calculate diluted income per share (in Shares)	26,170	26,664	26,279
Basic income from continuing operations per share applicable to common stockholders (in Dollars per share)	$ 3.09	$ 2.10	$ 0.52
Basic distributed income per share applicable to common stockholders (in Dollars per share)	$ (0.47)	$ (0.26)	$ (0.15)
Basic undistributed income from continuing operations per share applicable to common stockholders (in Dollars per share)	$ 2.62	$ 1.84	$ 0.37
Diluted income from continuing operations per share available to common stockholders (in Dollars per share)	$ 3.03	$ 2.07	$ 0.52
Diluted distributed income from continuing operations per share applicable to common stockholders (in Dollars per share)	$ (0.47)	$ (0.26)	$ (0.15)
Diluted undistributed income from continuing operations per share applicable to common stockholders (in Dollars per share)	$ 2.56	$ 1.81	$ 0.37
Numerator:
Diluted undistributed income from continuing operations applicable to common stockholders	67,329	48,388	9,668
Common Class B [Member]
Numerator:
Income from continuing operations applicable to common stockholders	10,326	7,918	1,961
Undistributed income from continuing operations applicable to common stockholders	8,757	6,940	1,395
Denominator:
Weighted average number of shares outstanding used to calculate basic income per share (in Shares)	3,342	3,762	3,762
Weighted average number of shares outstanding used to calculate diluted income per share (in Shares)	3,342	3,762	3,762
Basic income from continuing operations per share applicable to common stockholders (in Dollars per share)	$ 3.09	$ 2.10	$ 0.52
Basic distributed income per share applicable to common stockholders (in Dollars per share)	$ (0.47)	$ (0.26)	$ (0.15)
Basic undistributed income from continuing operations per share applicable to common stockholders (in Dollars per share)	$ 2.62	$ 1.84	$ 0.37
Diluted income from continuing operations per share available to common stockholders (in Dollars per share)	$ 3.03	$ 2.07	$ 0.52
Diluted distributed income from continuing operations per share applicable to common stockholders (in Dollars per share)	$ (0.47)	$ (0.26)	$ (0.15)
Diluted undistributed income from continuing operations per share applicable to common stockholders (in Dollars per share)	$ 2.56	$ 1.81	$ 0.37
Numerator:
Diluted undistributed income from continuing operations applicable to common stockholders	$ 8,598	$ 6,827	$ 1,384