Quarterly Results (unaudited) - Quarterly Financial Data and Operating Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013 Contract Settlements Backlog	Sep. 30, 2013 Settlements Contract Backlog	Jun. 30, 2013 Backlog Contract Settlements	Mar. 31, 2013 Contract Backlog Settlements	Dec. 31, 2012 Contract Settlements Backlog	Sep. 30, 2012 Backlog Contract Settlements	Jun. 30, 2012 Settlements Backlog Contract	Mar. 31, 2012 Settlements Backlog Contract	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information [Line Items]
Net income	$ 97,811	$ 82,935	$ 50,690	$ 35,041	$ 60,627	$ 53,000	$ 46,838	$ 20,123	$ 266,477	$ 180,588	$ 129,420
Diluted earnings per share	$ 21.15	$ 17.67	$ 10.11	$ 6.84	$ 11.98	$ 10.33	$ 8.97	$ 3.90	$ 54.81	$ 35.12	$ 23.01
Contracts for sale, net of cancellations (units)	2,631	2,381	3,278	3,510	2,625	2,558	2,614	3,157
Settlements (units)	3,342	3,342	2,878	2,272	2,788	2,656	2,475	1,924
Backlog, end of period (units)	4,945	5,656	6,617	6,217	4,979	4,950	5,048	4,909
Loans closed	721,926	695,930	646,450	473,766	642,171	594,867	548,871	420,184
Homebuilding [Member]
Quarterly Financial Information [Line Items]
Revenues-homebuilding operations	1,223,808	1,167,595	992,210	750,868	925,363	854,396	755,290	586,195	4,134,481	3,121,244	2,611,195
Gross profit - homebuilding operations	222,393	203,179	157,922	126,783	168,967	151,960	130,312	94,366
Mortgage Banking [Member]
Quarterly Financial Information [Line Items]
Mortgage banking fees	$ 18,344	$ 21,372	$ 17,682	$ 19,388	$ 18,375	$ 16,241	$ 14,493	$ 14,297	$ 76,786	$ 63,406	$ 47,954