Equity - Nonvested Restricted Stock Activity (Details)	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Number of Restricted Stock Shares
Non-vested at December 31, 2017 (in shares) | shares	5,748,408
Granted (in shares) | shares	1,730,214
Vested (in shares) | shares	(2,490,257)
Forfeited (in shares) | shares	(150,134)
Non-vested at March 31, 2018 (in shares) | shares	4,838,231
Weighted Average Grant-Date Fair Value per Share
Non-vested at December 31, 2017 (in dollars per share) | $ / shares	$ 52.78
Granted (in dollars per share) | $ / shares	67.24
Vested (in dollars per share) | $ / shares	49.46
Forfeited (in dollars per share) | $ / shares	57.22
Non-vested at March 31, 2018 (in dollars per share) | $ / shares	$ 59.52