Ownership, Description of Business, and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	May. 31, 2015	May. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Aug. 12, 2015	May. 06, 2014	Apr. 24, 2014	Mar. 05, 2014	Jun. 24, 2013	Nov. 27, 2012
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Foreclosure rate (less than)			0.50%
Deferred Court Costs not recovered, years			5 years
Receivables secured by property tax liens on non-accrual basis			$ 700,000	$ 0
Receivables secured by tax lien, redemption period (less than)			84 months
Receivables secured by property tax liens, net			$ 306,380,000	259,432,000
Stock repurchase program, authorized amount						$ 50,000,000.0		$ 50,000,000.0
Stock repurchased during period (in shares)	839,295	400,000
Stock repurchased during period (amount)	$ 33,200,000	$ 16,800,000	$ 33,185,000	$ 16,815,000	$ 729,000
Employee stock options to purchase common shares, excluded from computation of diluted earnings per share			0	0	0
2017 Convertible Senior Notes [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Debt instrument, interest rate			3.00%
Convertible debt			$ 115,000,000
Initial conversion price (in dollars per share)			$ 31.56								$ 31.56
2017 Convertible Senior Notes [Member] | Adjusted Debt Conversion Rate Following Hedge Transactions [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Initial conversion price (in dollars per share)			$ 60.00
2020 Convertible Senior Notes [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Debt instrument, interest rate			3.00%
Convertible debt			$ 172,500,000
Initial conversion price (in dollars per share)			$ 45.72							$ 45.72
2020 Convertible Senior Notes [Member] | Adjusted Debt Conversion Rate Following Hedge Transactions [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Initial conversion price (in dollars per share)			$ 61.55
2021 Convertible Senior Notes [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Debt instrument, interest rate			2.875%
Convertible debt			$ 161,000,000
Initial conversion price (in dollars per share)			$ 59.39						$ 59.39
2021 Convertible Senior Notes [Member] | Adjusted Debt Conversion Rate Following Hedge Transactions [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Initial conversion price (in dollars per share)			$ 83.14
Texas [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Receivables secured by property tax liens, net							$ 141,500,000
Receivables secured by property tax liens, principal balance							$ 134,000,000
Debt instrument, interest rate							1.44%
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Receivables secured by property tax liens, net			$ 81,149,000	$ 108,535,000