Net Income(loss) per common share - Additonal Information (Details) - $ / shares shares in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Jun. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		8	14
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Basic Earnings Per Share	$ 0.01	$ 0.02
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Diluted Earnings Per Share	$ 0.01	$ 0.02