Note 16 - Stock-based Compensation - Performance Stock Units Granted (Details) - Performance Shares [Member] $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares
Maximum potential expense to be recognized | $	$ 17,604,000
July 25, 2016 [Member]
Maximum potential expense to be recognized | $	10,834,000	[1]
June 20, 2017 [Member]
Maximum potential expense to be recognized | $	16,070,000	[1]
May 23, 2018 [Member]
Maximum potential expense to be recognized | $	14,915,000	[1]
Chief Operating Officer [Member] | July 25, 2016 [Member]
Base period revenues | $	$ 1,975
Threshold goal, number of PSUs (in shares)	61,236
Threshold goal, home sale revenues | $	$ 2,074
Target goal, number of PSUs (in shares)	122,472
Target goal, home sale revenues | $	$ 2,173
Maximum goal, number of PSUs (in shares)	244,944
Maximum goal, home sale revenues | $	$ 2,370
Maximum potential expense to be recognized | $	$ 4,815,000	[1]
Fair value per share (in dollars per share) | $ / shares	$ 19.66
Chief Operating Officer [Member] | June 20, 2017 [Member]
Base period revenues | $	$ 2,426
Threshold goal, number of PSUs (in shares)	64,152
Threshold goal, home sale revenues | $	$ 2,547
Target goal, number of PSUs (in shares)	128,304
Target goal, home sale revenues | $	$ 2,669
Maximum goal, number of PSUs (in shares)	256,608
Maximum goal, home sale revenues | $	$ 2,911
Maximum potential expense to be recognized | $	$ 7,142,000	[1]
Fair value per share (in dollars per share) | $ / shares	$ 27.83
Chief Operating Officer [Member] | May 23, 2018 [Member]
Base period revenues | $	$ 2,543
Threshold goal, number of PSUs (in shares)	64,800
Threshold goal, home sale revenues | $	$ 2,670
Target goal, number of PSUs (in shares)	129,600
Target goal, home sale revenues | $	$ 2,797
Maximum goal, number of PSUs (in shares)	259,200
Maximum goal, home sale revenues | $	$ 3,052
Maximum potential expense to be recognized | $	$ 6,629,000	[1]
Fair value per share (in dollars per share) | $ / shares	$ 25.57
Chief Operating Officer [Member] | August 5, 2019 [Member]
Base period revenues | $	$ 2,982
Threshold goal, number of PSUs (in shares)	60,000
Threshold goal, home sale revenues | $	$ 3,131
Target goal, number of PSUs (in shares)	120,000
Target goal, home sale revenues | $	$ 3,280
Maximum goal, number of PSUs (in shares)	240,000
Maximum goal, home sale revenues | $	$ 3,578
Maximum potential expense to be recognized | $	$ 7,824,000
Fair value per share (in dollars per share) | $ / shares	$ 32.60
Chief Executive Officer [Member] | July 25, 2016 [Member]
Threshold goal, number of PSUs (in shares)	61,236
Target goal, number of PSUs (in shares)	122,472
Maximum goal, number of PSUs (in shares)	244,944
Maximum potential expense to be recognized | $	$ 4,815,000	[1]
Chief Executive Officer [Member] | June 20, 2017 [Member]
Threshold goal, number of PSUs (in shares)	64,152
Target goal, number of PSUs (in shares)	128,304
Maximum goal, number of PSUs (in shares)	256,608
Maximum potential expense to be recognized | $	$ 7,142,000	[1]
Chief Executive Officer [Member] | May 23, 2018 [Member]
Threshold goal, number of PSUs (in shares)	64,800
Target goal, number of PSUs (in shares)	129,600
Maximum goal, number of PSUs (in shares)	259,200
Maximum potential expense to be recognized | $	$ 6,629,000	[1]
Chief Executive Officer [Member] | August 5, 2019 [Member]
Threshold goal, number of PSUs (in shares)	60,000
Target goal, number of PSUs (in shares)	120,000
Maximum goal, number of PSUs (in shares)	240,000
Maximum potential expense to be recognized | $	$ 7,824,000
Chief Financial Officer [Member] | July 25, 2016 [Member]
Threshold goal, number of PSUs (in shares)	15,309
Target goal, number of PSUs (in shares)	30,618
Maximum goal, number of PSUs (in shares)	61,236
Maximum potential expense to be recognized | $	$ 1,204,000	[1]
Chief Financial Officer [Member] | June 20, 2017 [Member]
Threshold goal, number of PSUs (in shares)	16,038
Target goal, number of PSUs (in shares)	32,076
Maximum goal, number of PSUs (in shares)	64,152
Maximum potential expense to be recognized | $	$ 1,786,000	[1]
Chief Financial Officer [Member] | May 23, 2018 [Member]
Threshold goal, number of PSUs (in shares)	16,200
Target goal, number of PSUs (in shares)	32,400
Maximum goal, number of PSUs (in shares)	64,800
Maximum potential expense to be recognized | $	$ 1,657,000	[1]
Chief Financial Officer [Member] | August 5, 2019 [Member]
Threshold goal, number of PSUs (in shares)	15,000
Target goal, number of PSUs (in shares)	30,000
Maximum goal, number of PSUs (in shares)	60,000
Maximum potential expense to be recognized | $	$ 1,956,000

[1] Dollars in thousands