Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share (Tables) [Abstract]

Computation of basic and diluted earnings per share

		Year Ended December 31,
		2017		2016		2015
Numerator for basic and diluted earnings per share -
	net income attributable to common stockholders	$	463,595	$	1,012,397	$	818,344
Denominator for basic earnings per
	share: weighted-average shares		367,237		358,275		348,240
Effect of dilutive securities:
	Employee stock options		47		110		143
	Non-vested restricted shares		482		449		535
	Redeemable shares		1,235		1,393		310
	Convertible senior unsecured notes		-		-		196
Dilutive potential common shares			1,764		1,952		1,184
Denominator for diluted earnings per
	share: adjusted-weighted average shares		369,001		360,227		349,424
Basic earnings per share		$	1.26	$	2.83	$	2.35
Diluted earnings per share		$	1.26	$	2.81	$	2.34