Note 16 - Stock-based Compensation - Performance Stock Units Granted (Details) - Performance Shares [Member] $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares
July 25, 2016 [Member]
Maximum potential expense to be recognized | $	$ 10,834
June 20, 2017 [Member]
Maximum potential expense to be recognized | $	16,070
May 23, 2018 [Member]
Maximum potential expense to be recognized | $	$ 14,915
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
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
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
Chief Operating 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
Base period revenues | $	1,975,000
Threshold goal, home sale revenues | $	2,074,000
Target goal, home sale revenues | $	2,173,000
Maximum goal, home sale revenues | $	$ 2,370,000
Fair value per share (in dollars per share) | $ / shares	$ 19.66
Chief Operating 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
Base period revenues | $	2,426,000
Threshold goal, home sale revenues | $	2,547,000
Target goal, home sale revenues | $	2,669,000
Maximum goal, home sale revenues | $	$ 2,911,000
Fair value per share (in dollars per share) | $ / shares	$ 27.83
Chief Operating 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
Base period revenues | $	2,543,000
Threshold goal, home sale revenues | $	2,670,000
Target goal, home sale revenues | $	2,797,000
Maximum goal, home sale revenues | $	$ 3,052,000
Fair value per share (in dollars per share) | $ / shares	$ 25.57
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
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
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