Joint Ventures - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Assets:
Cash	$ 387,462	$ 545,419	$ 466,293	$ 866,253
Land under development	53,203
Liabilities and equity:
Equity	1,240,490	1,124,255
Total liabilities and shareholders' equity	2,570,682	2,351,335
Consolidated Joint Venture
Assets:
Cash	1,169	481
Restricted cash		160
Other assets	228	332
Land under development	402	2,617
Total assets	1,799	3,590
Liabilities and equity:
Debt		64
Accrued expenses	1,318	1,231
Equity	481	2,295
Total liabilities and shareholders' equity	$ 1,799	$ 3,590