Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	May. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Equity [Line Items]
Company repurchased, shares	2,300,000
Repurchase of Company stock for retirement	$ 100,000,000			$ 100,028,000
Cash Dividend on Common Stock		$ 2.70	$ 2.20	$ 2.00
Aggregated Dividend Paid		$ 138,400,000	$ 112,000,000	$ 101,700,000
Minimum percentage of adjusted funds from operations as cash dividend		50.00%
Percentage of REIT taxable income as cash dividend		100.00%
2015 Stock Repurchase Program [Member]
Schedule Of Equity [Line Items]
Authorized amount for share repurchase program		$ 100,000,000
Company repurchased, shares		0