Organization and Nature of Operations (Details) - USD ($)			3 Months Ended		9 Months Ended
	Aug. 19, 2016	Aug. 15, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Aug. 16, 2016	May 27, 2016	Dec. 31, 2015
Organization And Nature Of Operations [Line Items]
Net proceeds after deducting underwriting discount and commission and offering expenses					$ 930,315,000	$ 441,000,000
Premium on senior unsecured notes			$ 8,042,000		8,042,000				$ 4,660,000
Cash paid for interest			$ 21,668,000	$ 21,296,000	$ 42,909,000	$ 43,306,000
Common Stock, Class A
Organization And Nature Of Operations [Line Items]
Common stock, par value (in dollars per share)			$ 0.01		$ 0.01				$ 0.01
Common Stock | Common Stock, Class A
Organization And Nature Of Operations [Line Items]
Issuance of Class A Common Stock					38,812,000
Common Stock | Common Stock, Class A | Public Offering
Organization And Nature Of Operations [Line Items]
Issuance of Class A Common Stock		8,337,500
Common stock, par value (in dollars per share)		$ 0.01
Option to purchase additional shares		1,087,500
Stock price per share at public offering		$ 33.55
Gross proceeds received from public offering	$ 279,700,000
Net proceeds after deducting underwriting discount and commission and offering expenses	271,100,000
Senior Notes | 6.250% senior unsecured notes due 2024
Organization And Nature Of Operations [Line Items]
Face amount							$ 200,000,000.0
Debt instrument interest rate stated percentage			6.25%		6.25%		6.25%
Offering price as percentage of par							102.00%
Gross proceeds from debt issuance	206,800,000
Premium on senior unsecured notes	4,000,000
Cash paid for interest	2,800,000
Proceeds from debt issuance, net	$ 199,600,000
Senior Notes | 6.250% Initial 2024 Notes
Organization And Nature Of Operations [Line Items]
Face amount								$ 200,000,000.0
Debt instrument interest rate stated percentage								6.25%