Quarterly Results (unaudited) - Quarterly Financial Data and Operating Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($) Settlements Backlog order $ / shares	Sep. 30, 2019 USD ($) Settlements Backlog order $ / shares	Jun. 30, 2019 USD ($) Settlements Backlog order $ / shares	Mar. 31, 2019 USD ($) Settlements Backlog order $ / shares	Dec. 31, 2018 USD ($) Settlements Backlog order $ / shares	Sep. 30, 2018 USD ($) Settlements Backlog order $ / shares	Jun. 30, 2018 USD ($) Settlements Backlog order $ / shares	Mar. 31, 2018 USD ($) Settlements Backlog order $ / shares	Dec. 31, 2019 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares
Quarterly Financial Information [Line Items]
Revenues									$ 7,388,664	$ 7,163,674	$ 6,305,840
Loans closed	$ 1,418,742	$ 1,373,946	$ 1,231,039	$ 1,140,999	$ 1,356,430	$ 1,249,199	$ 1,214,101	$ 1,009,673
Net income	$ 256,137	$ 223,787	$ 210,209	$ 188,406	$ 232,158	$ 195,816	$ 203,174	$ 166,049	$ 878,539	$ 797,197	$ 537,521
Diluted earnings per share | $ / shares	$ 64.41	$ 56.11	$ 53.09	$ 47.64	$ 58.57	$ 48.28	$ 49.05	$ 39.34	$ 221.13	$ 194.80	$ 126.77
New orders (units) | order	4,392	4,766	5,239	5,139	3,841	4,302	4,964	5,174
Settlements (units) | Settlements	5,331	5,124	4,720	4,493	5,186	4,754	4,611	3,896
Backlog (units) | Backlog	8,233	9,172	9,530	9,011	8,365	9,710	10,162	9,809
Homebuilding:
Quarterly Financial Information [Line Items]
Gross profit	$ 379,467	$ 355,055	$ 332,060	$ 304,400	$ 363,668	$ 336,696	$ 333,666	$ 278,147
Revenues	1,946,859	1,873,331	1,757,448	1,643,206	1,954,403	1,809,345	1,750,463	1,490,093	$ 7,220,844	$ 7,004,304	$ 6,175,521
Mortgage Banking:
Quarterly Financial Information [Line Items]
Revenues	$ 43,336	$ 37,933	$ 42,746	$ 43,805	$ 40,145	$ 43,062	$ 36,842	$ 39,321	$ 167,820	$ 159,370	$ 130,319