Fair Value Measurements (Carrying Amounts and Estimated Fair Values of Financial Instruments Not Measured at Fair Value) (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Carrying Amount
Assets:
Cash and cash equivalents	$ 1,443,312	$ 1,027,321
Deposits with banks	22,257	23,224
Notes receivable, net	7,007	5,866
Liabilities:
Deposits	3,218,128	2,699,015
Notes and contracts payable	737,944	581,052
Estimated Fair Value
Assets:
Cash and cash equivalents	1,443,312	1,027,321
Deposits with banks	22,214	23,211
Notes receivable, net	6,893	5,791
Liabilities:
Deposits	3,218,128	2,699,015
Notes and contracts payable	763,860	590,970
Estimated Fair Value | Level 1
Assets:
Cash and cash equivalents	1,443,312	1,027,321
Deposits with banks	1,110	1,103
Notes receivable, net	0	0
Liabilities:
Deposits	3,218,128	2,699,015
Notes and contracts payable	0	0
Estimated Fair Value | Level 2
Assets:
Cash and cash equivalents	0	0
Deposits with banks	21,104	22,108
Notes receivable, net	0	0
Liabilities:
Deposits	0	0
Notes and contracts payable	758,073	583,893
Estimated Fair Value | Level 3
Assets:
Cash and cash equivalents	0	0
Deposits with banks	0	0
Notes receivable, net	6,893	5,791
Liabilities:
Deposits	0	0
Notes and contracts payable	$ 5,787	$ 7,077