Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2013	Oct. 06, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flows From Operating Activities
Net income (loss)	$ 193,431	$ (37,232)	$ 70,210		$ 48,643
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	27,375		145,431
Amortization of deferred finance costs and debt premiums and discount	152		3,956
Amortization of acquired above and below-market leases, net	(1,911)		(14,095)	(1,903)	0
Amortization of acquired below-market ground lease	426		4,603
Straight-lining of rental revenue	(8,932)		(39,715)
Equity based compensation	2,994		3,720
Gain on consolidation of non-controlled entities	(322,563)		0
Equity in net income of non-controlled entities	0	(14,875)	0		(14,348)
Distributions of cumulative earnings of non-controlled entities	0		0
Deemed contribution for settlement expense	0	55,000	0
Increase (decrease) in cash flows due to changes in operating assets and liabilities (excluding the effect of acquisitions):
Restricted cash	7,196		(4,987)
Tenant and other receivables	(7,590)		3,135
Deferred leasing costs	(8,916)		(12,132)
Prepaid expenses and other assets	(15,120)		(13,052)
Accounts payable and accrued expenses	11,917		(14,756)
Deferred revenue and other liabilities	(10,386)		6,240
Net cash provided by (used in) operating activities	(131,927)		138,558
Cash Flows From Investing Activities
Decrease (increase) in restricted cash for investing activities	(344)		9,345
Acquisition of real estate property, net of cash received	0		(186,588)
Cash paid in the formation transactions to acquire the non-controlled properties, net of cash received	(563,529)		0
Development costs	0		(527)
Increase in due from affiliates for advances for leasehold interests and improvements	0		0
Additions to building and improvements	(56,434)		(121,287)
Net cash used in investing activities	(620,307)		(299,057)
Cash Flows From Financing Activities
Proceeds from mortgage notes payable	0		191,000
Repayment of mortgage notes payable	(313,240)		(348,308)
Proceeds from unsecured loan payable	0		0
Repayment of unsecured notes payable	(7,350)		0
Proceeds from senior unsecured notes	0	0	250,000		0
Proceeds from term loan and credit facility	335,000		435,600
Repayments of term loan and credit facility	(10,000)		(290,600)
Deferred financing costs and equity issuance costs	(15,381)		(4,483)
Net proceeds from the sale of common stock	992,887		0
Deferred offering costs	0		0
Contributions from owners	0		0
Cash paid for equity interests in the formation transactions	(143,236)		0
Distributions to Predecessor owners	(123,147)		0
Private perpetual preferred unit distributions	0	0	(476)		0
Dividends paid to common stockholders	(7,601)		(33,598)
Distributions paid to noncontrolling interests in the operating partnership	(11,915)		(53,647)
Net cash provided by (used in) financing activities	696,017		145,488
Net increase (decrease) in cash and cash equivalents	(56,217)		(15,011)
Cash and cash equivalents—beginning of period	116,960		60,743
Cash and cash equivalents—end of period	60,743	116,960	45,732	60,743
Supplemental disclosures of cash flow information:
Cash paid for interest	12,648		60,621
Cash paid for income taxes	329		3,690
Non-cash investing and financing activities:
Commercial real estate properties included in accounts payable and accrued expenses	15,584		36,920
Issuance of Class A Common Stock, Class B Common Stock, and operating partnership units in connection with the acquisition of real estate properties	457,493		379,328
Debt assumed with the acquisition of real estate properties	136,226		182,851
Reduction of equity for deferred offering costs	32,319		0
Acquisition of working capital, net of cash	6,061		(4,749)
Due to affiliates settled in Class A Common Stock, Class B Common Stock, or operating partnership units	4,299		0
Conversion of operating partnership units and Class B shares to Class A shares	0	0	40,611		0
Redemption of operating partnership units to repay other receivable	0	0	829		0
Accrued distributions to Predecessor owners	0		0
Distribution of real property to owners prior to the formation transactions	0		0
Distribution of unsecured loan and note payable - related party to owners prior to the formation transactions	0		0
Predecessor [Member]
Cash Flows From Operating Activities
Net income (loss)		(37,232)			48,643
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization		38,963			42,690
Amortization of deferred finance costs and debt premiums and discount		11,512			4,881
Amortization of acquired above and below-market leases, net		0			0
Amortization of acquired below-market ground lease		0			0
Straight-lining of rental revenue		(3,383)			(2,568)
Equity based compensation		0			0
Gain on consolidation of non-controlled entities		0			0
Equity in net income of non-controlled entities		(14,875)			(14,348)
Distributions of cumulative earnings of non-controlled entities		3,391			10,095
Deemed contribution for settlement expense		55,000			0
Increase (decrease) in cash flows due to changes in operating assets and liabilities (excluding the effect of acquisitions):
Restricted cash		(633)			4,392
Tenant and other receivables		(80)			4,484
Deferred leasing costs		(9,771)			(14,654)
Prepaid expenses and other assets		3,084			(1,154)
Accounts payable and accrued expenses		26,481			10,383
Deferred revenue and other liabilities		924			1,509
Net cash provided by (used in) operating activities		73,381			94,353
Cash Flows From Investing Activities
Decrease (increase) in restricted cash for investing activities		(500)			(5,561)
Acquisition of real estate property, net of cash received		0			0
Cash paid in the formation transactions to acquire the non-controlled properties, net of cash received		0			0
Development costs		179			(189)
Increase in due from affiliates for advances for leasehold interests and improvements		0			(15,061)
Additions to building and improvements		(56,129)			(87,470)
Net cash used in investing activities		(56,450)			(108,281)
Cash Flows From Financing Activities
Proceeds from mortgage notes payable		102,947			69,000
Repayment of mortgage notes payable		(20,049)			(12,212)
Proceeds from unsecured loan payable		3,750			51
Repayment of unsecured notes payable		0			0
Proceeds from term loan and credit facility		0			0
Repayments of term loan and credit facility		0			0
Deferred financing costs and equity issuance costs		(3,482)			(4,339)
Net proceeds from the sale of common stock		0			0
Deferred offering costs		(6,595)			(12,593)
Contributions from owners		3,924			2,107
Cash paid for equity interests in the formation transactions		0			0
Distributions to Predecessor owners		(31,965)			(62,903)
Dividends paid to common stockholders		0			0
Distributions paid to noncontrolling interests in the operating partnership		0			0
Net cash provided by (used in) financing activities		48,530			(20,889)
Net increase (decrease) in cash and cash equivalents		65,461			(34,817)
Cash and cash equivalents—beginning of period		51,499		51,499	86,316
Cash and cash equivalents—end of period		116,960			51,499
Supplemental disclosures of cash flow information:
Cash paid for interest		38,380			48,993
Cash paid for income taxes		0			0
Non-cash investing and financing activities:
Commercial real estate properties included in accounts payable and accrued expenses		1,812			1,926
Issuance of Class A Common Stock, Class B Common Stock, and operating partnership units in connection with the acquisition of real estate properties		0			0
Debt assumed with the acquisition of real estate properties		0			0
Reduction of equity for deferred offering costs		0			0
Acquisition of working capital, net of cash		0			0
Due to affiliates settled in Class A Common Stock, Class B Common Stock, or operating partnership units		0			0
Accrued distributions to Predecessor owners		123,147			0
Distribution of real property to owners prior to the formation transactions		16,345			0
Distribution of unsecured loan and note payable - related party to owners prior to the formation transactions		$ 14,739			$ 0