Incentive Based Compensation - Stock Options, Restricted Stock Awards and Restricted Stock Units (Details)	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Number of Shares
Outstanding, beginning (in shares) | shares	6,180,007
Granted (in shares) | shares	648,526
Options Exercised (in shares) | shares	(10,470)
Canceled (in shares) | shares	(151,412)
Outstanding, ending (in shares) | shares	6,666,651
Weighted Average Exercise Price
Outstanding, beginning (in dollars per share)	$ 24.39
Granted (in dollars per share)	16.79
Options Exercised (in dollars per share)	14.92
Canceled (in dollars per share)	27.15
Outstanding, ending (in dollars per share)	23.60
Weighted Average Grant Date Fair Value
Weighted average grant date fair value (in dollars per share)	$ 6.62
Restricted Stock Awards & Units
Awards
Outstanding, beginning (in shares) | shares	8,504,946
Granted (in shares) | shares	3,824,208
Stock Vested (in shares) | shares	(3,519,699)
Canceled (in shares) | shares	(157,302)
Outstanding, ending (in shares) | shares	8,652,153
Weighted Average Grant Date Fair Value
Outstanding, beginning (in dollars per share)	$ 14.04
Granted (in dollars per share)	16.98
Stock Vested (in dollars per share)	12.37
Canceled (in dollars per share)	14.58
Outstanding, ending (in dollars per share)	$ 16.01