Organization, Basis of Presentation, and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of reconciliation of income from book basis to tax basis

The following reconciles net income attributable to common stockholders to taxable net income for the years ended December 31, 2017, 2016 and 2015 (unaudited, dollars in thousands):

	2017 Estimate			2016 Actual			2015 Actual
Net income attributable to common stockholders	$	876,921		$	1,034,002		$	742,038
GAAP gain on sale of communities (in excess of) less than tax gain	(85,873		)	(195,029		)	(20,900		)
Depreciation/amortization timing differences on real estate	11,868			(947		)	(24,657		)
Amortization of debt/mark to market interest	(17,430		)	(18,985		)	(64,676		)
Tax compensation expense less than (in excess of) GAAP	(3,828		)	9,821			(1,244		)
Casualty and impairment (gain) loss, net	6,250			(657		)	(10,542		)
Other adjustments	(40,381		)	11,533			(12,829		)
Taxable net income	$	747,527		$	839,738		$	607,190

Schedule of tax components of the entity's common dividends declared

The following summarizes the tax components of the Company's common dividends declared for the years ended December 31, 2017, 2016 and 2015 (unaudited):

	2017		2016		2015
Ordinary income	75	%	68	%	83	%
20% capital gain	18	%	26	%	12	%
Unrecaptured §1250 gain	7	%	6	%	5	%

Schedule of earnings per common share

The Company's earnings per common share are determined as follows (dollars in thousands, except per share data):

	For the year ended
	12/31/17			12/31/16			12/31/15
Basic and diluted shares outstanding
Weighted average common shares—basic	137,523,771			136,928,251			133,565,711
Weighted average DownREIT units outstanding	7,500			7,500			7,500
Effect of dilutive securities	535,415			525,886			1,019,966
Weighted average common shares—diluted	138,066,686			137,461,637			134,593,177
Calculation of Earnings per Share—basic
Net income attributable to common stockholders	$	876,921		$	1,034,002		$	742,038
Net income allocated to unvested restricted shares	(2,463		)	(2,610		)	(1,774		)
Net income attributable to common stockholders, adjusted	$	874,458		$	1,031,392		$	740,264
Weighted average common shares—basic	137,523,771			136,928,251			133,565,711
Earnings per common share—basic	$	6.36		$	7.53		$	5.54
Calculation of Earnings per Share—diluted
Net income attributable to common stockholders	$	876,921		$	1,034,002		$	742,038
Add: noncontrolling interests of DownREIT unitholders in consolidated partnerships, including discontinued operations	42			41			38
Adjusted net income attributable to common stockholders	$	876,963		$	1,034,043		$	742,076
Weighted average common shares—diluted	138,066,686			137,461,637			134,593,177
Earnings per common share—diluted	$	6.35		$	7.52		$	5.51
Dividends per common share	$	5.68		$	5.40		$	5.00

Schedule of New Accounting Pronouncements and Changes in Accounting Principles

The following tables present the impact of the two changes in accounting principle to the Consolidated Statement of Cash Flows for the years ended December 31, 2016 and 2015 (dollars in thousands):

	12/31/2016 (as previously reported)			Impact of ASU 2016-09			Impact of ASU 2016-18			12/31/2016 (as adjusted and currently reported)
Net cash provided by operating activities	1,143,484			8,562			8,226			1,160,272
Net cash used in investing activities	(1,037,352		)	—			5,000			(1,032,352		)
Net cash used in financing activities	(291,645		)	(8,562		)	(3,064		)	(303,271		)
Net decrease in cash, cash equivalents	(185,513		)	—			185,513			—
Net decrease in cash, cash equivalents and restricted cash	—			—			(175,351		)	(175,351		)
Cash, cash equivalents, beginning of period	400,507			—			(400,507		)	—
Cash, cash equivalents and restricted cash, beginning of period	—			—			505,328			505,328
Cash, cash equivalents, end of period	$	214,994		—			—			—
Cash, cash equivalents and restricted cash, end of period				$	—		$	114,983		$	329,977

	12/31/2015 (as previously reported)			Impact of ASU 2016-09			Impact of ASU 2016-18			12/31/2015 (as adjusted and currently reported)
Net cash provided by operating activities	1,056,754			6,076			11,837			1,074,667
Net cash used in investing activities	(1,199,517		)	—			—			(1,199,517		)
Net cash provided by (used in) financing activities	33,810			(6,076		)	(2,641		)	25,093
Net decrease in cash, cash equivalents	(108,953		)	—			108,953			—
Net decrease in cash, cash equivalents and restricted cash	—			—			(99,757		)	(99,757		)
Cash, cash equivalents, beginning of period	509,460			—			(509,460		)	—
Cash, cash equivalents and restricted cash, beginning of period	—			—			605,085			605,085
Cash, cash equivalents, end of period	$	400,507		—			—			—
Cash, cash equivalents and restricted cash, end of period				$	—		$	104,821		$	505,328