Equity - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended				0 Months Ended	6 Months Ended	0 Months Ended	6 Months Ended	0 Months Ended										3 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Jun. 13, 2014 Installment 2 Fiscal Year 2014 [Member]	Jun. 30, 2014 Installment 2 Fiscal Year 2014 [Member]	Mar. 14, 2014 Installment 1 Fiscal Year 2014 [Member]	Jun. 30, 2014 Installment 1 Fiscal Year 2014 [Member]	May 09, 2014 Class A Common Stock [Member]	Apr. 07, 2014 Class A Common Stock [Member]	Jan. 14, 2014 Class A Common Stock [Member]	Apr. 07, 2014 Class A Common Stock [Member]	Jan. 14, 2014 Class A Common Stock [Member]	May 31, 2013 Class A Common Stock [Member]	Jun. 30, 2014 Class A Common Stock [Member] Direct Stock Purchase Plan [Member]	Jun. 30, 2014 Class A Common Stock [Member] Dividend Reinvestment Plan [Member]	Jun. 30, 2014 Class A Common Stock [Member] Dividend Reinvestment And Direct Stock Purchase Plan [Member]	Mar. 25, 2014 Class A Common Stock [Member] Dividend Reinvestment And Direct Stock Purchase Plan [Member]	Jun. 30, 2014 Class A Common Stock [Member] Joshua A. Polan [Member]
Class of Stock [Line Items]
Increase in total equity		$ 525,300,000
Total equity	1,282,025,000	1,282,025,000	801,667,000	756,750,000	153,453,000
Total stock, shares authorized	200,000,000	200,000,000
Common stock, shares authorized	100,000,000	100,000,000		100,000,000
Preferred stock, shares authorized	100,000,000	100,000,000
Additional shares issued													9,200,000	9,775,000
Additional shares, public offering price														$ 26.25
Issuance of additional shares, net proceeds after underwriting discounts and other offering expenses											254,800,000	256,100,000
Additional shares, public offering price													$ 27.72
Shares issued for deferred stock units upon resignation																				2,851
Aggregate sales price										200,000,000
Preferred stock issued	0	0
Preferred stock outstanding	0	0
Dividends paid		32,129,000	0				23,300,000		18,900,000
Dividends per common stock	$ 0.48	$ 0.96				$ 0.48		$ 0.48
Date of dividend paid							Jul. 15, 2014		Apr. 15, 2014
Date of dividend declared							Jun. 13, 2014		Mar. 14, 2014
Record date of dividend paid							Jun. 30, 2014		Mar. 31, 2014
Plan adoption date		March 25, 2014
Common stock issued	47,935,000	47,935,000		28,802,000											25,875,000	0	1
Reserved for issuance of class A common stock																		9,999,999	10,000,000
Accumulated other comprehensive income	2,728,000	2,728,000	0	798,000
Unrealized gain on foreign currency remeasurement	$ 1,894,000	$ 1,930,000