Share-Based Compensation - Breakdown of the Closing Balance (Details)	12 Months Ended
	Dec. 31, 2016 $ / shares shares	Dec. 31, 2015 $ / shares shares	Dec. 31, 2014 $ / shares shares	Dec. 31, 2016 € / shares shares	Dec. 31, 2015 € / shares shares	Dec. 31, 2014 € / shares shares	Dec. 31, 2013 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, weighted-average exercise price, options (in Euro per share) | € / shares				€ 23.92	€ 20.97	€ 14.10
Number exercisable (in shares)	2,708,406,000	2,644,220,000	2,662,969,000	2,708,406,000	2,644,220,000	2,662,969,000
Exercisable, weighted-average exercise price, options (in Euro per share) | € / shares				€ 17.73	€ 11.85	€ 5.81
Weighted-average remaining contractual life, options (in years)	6 years 10 months 24 days	7 years 10 months 24 days	8 years 2 months 12 days
Number outstanding, equity awards (in shares)	8,203,371,000	7,643,439,000	7,355,841,000	8,203,371,000	7,643,439,000	7,355,841,000	8,518,309,000
BSA
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, options (in shares)	188,125,000	154,910,000	199,408,000	188,125,000	154,910,000	199,408,000	542,148,000
Outstanding, weighted-average exercise price, options (in Euro per share) | $ / shares	$ 19.04	$ 15.72	$ 7.54
Number of exercisable options (in shares)	117,096,000	117,783,000	155,609,000	117,096,000	117,783,000	155,609,000
Exercisable, weighted-average exercise price, options (in Euro per share) | $ / shares	$ 11.73	$ 8.49	$ 6.88
Weighted-average remaining contractual life, options (in years)	7 years 3 months 18 days	7 years 4 months 24 days	7 years 6 months
RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, RSUs (in shares)	3,243,279,000	1,095,585,000	0	3,243,279,000	1,095,585,000	0	0
Plans 1 and 2 | OSA and BSPCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, options (in shares)	54,154,000	87,557,000	204,077,000	54,154,000	87,557,000	204,077,000	1,134,737,000
Outstanding, weighted-average exercise price, options (in Euro per share) | € / shares				€ 1.24	€ 1.41	€ 1.08
Number exercisable (in shares)	54,154,000	87,557,000	204,077,000	54,154,000	87,557,000	204,077,000
Exercisable, weighted-average exercise price, options (in Euro per share) | € / shares				€ 1.24	€ 1.41	€ 1.08
Weighted-average remaining contractual life, options (in years)	2 years 10 months 24 days	3 years 7 months 6 days	4 years 7 months 6 days
Plan 3 | OSA and BSPCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, options (in shares)	175,693,000	337,658,000	935,591,000	175,693,000	337,658,000	935,591,000	2,333,763,000
Outstanding, weighted-average exercise price, options (in Euro per share) | € / shares				€ 3.29	€ 3.14	€ 2.08
Number exercisable (in shares)	175,693,000	337,658,000	883,399,000	175,693,000	337,658,000	883,399,000
Exercisable, weighted-average exercise price, options (in Euro per share) | € / shares				€ 3.29	€ 3.14	€ 1.94
Weighted-average remaining contractual life, options (in years)	4 years 3 months 18 days	4 years 9 months 18 days	5 years 9 months 18 days
Plan 4 | OSA and BSPCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, options (in shares)	0	0	87,559,000	0	0	87,559,000	361,118,000
Outstanding, weighted-average exercise price, options (in Euro per share) | € / shares				€ 0.00	€ 0.00	€ 2.10
Number exercisable (in shares)	0	0	87,559,000	0	0	87,559,000
Exercisable, weighted-average exercise price, options (in Euro per share) | € / shares				€ 0.00	€ 0.00	€ 2.10
Weighted-average remaining contractual life, options (in years)			5 years 3 months 18 days
Plan 5 | OSA and BSPCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, options (in shares)	513,067,000	819,347,000	1,184,725,000	513,067,000	819,347,000	1,184,725,000	1,929,299,000
Outstanding, weighted-average exercise price, options (in Euro per share) | € / shares				€ 5.95	€ 5.95	€ 5.95
Number exercisable (in shares)	513,067,000	713,165,000	730,371,000	513,067,000	713,165,000	730,371,000
Exercisable, weighted-average exercise price, options (in Euro per share) | € / shares				€ 5.95	€ 5.95	€ 5.95
Weighted-average remaining contractual life, options (in years)	5 years 2 months 12 days	6 years 3 months 18 days	7 years 3 months 18 days
Plan 6 | OSA and BSPCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, options (in shares)	399,441,000	692,931,000	889,800,000	399,441,000	692,931,000	889,800,000	1,204,248,000
Outstanding, weighted-average exercise price, options (in Euro per share) | € / shares				€ 9.77	€ 9.75	€ 9.81
Number exercisable (in shares)	325,596,000	420,228,000	362,778,000	325,596,000	420,228,000	362,778,000
Exercisable, weighted-average exercise price, options (in Euro per share) | € / shares				€ 9.66	€ 9.58	€ 9.58
Weighted-average remaining contractual life, options (in years)	6 years 1 month 6 days	7 years 1 month 6 days	8 years 1 month 6 days
Plan 7 | OSA and BSPCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, options (in shares)	750,528,000	1,287,578,000	1,817,135,000	750,528,000	1,287,578,000	1,817,135,000	1,555,144,000
Outstanding, weighted-average exercise price, options (in Euro per share) | € / shares				€ 18.13	€ 17.97	€ 18.29
Number exercisable (in shares)	504,262,000	564,034,000	394,785,000	504,262,000	564,034,000	394,785,000
Exercisable, weighted-average exercise price, options (in Euro per share) | € / shares				€ 17.94	€ 17.24	€ 14.02
Weighted-average remaining contractual life, options (in years)	6 years 9 months 18 days	7 years 10 months 24 days	8 years 10 months 24 days
Plan 8 | OSA and BSPCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, options (in shares)	2,942,834,000	3,322,783,000	2,236,954,000	2,942,834,000	3,322,783,000	2,236,954,000	0
Outstanding, weighted-average exercise price, options (in Euro per share) | € / shares				€ 31.32	€ 30.50	€ 23.40
Number exercisable (in shares)	1,135,634,000	521,578,000	0	1,135,634,000	521,578,000	0
Exercisable, weighted-average exercise price, options (in Euro per share) | € / shares				€ 28.96	€ 23.32	€ 0.00
Weighted-average remaining contractual life, options (in years)	8 years 2 months 12 days	8 years 10 months 24 days	9 years 7 months 6 days
Plan 9 | OSA and BSPCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number outstanding, options (in shares)	124,375,000	0	0	124,375,000	0	0	0
Outstanding, weighted-average exercise price, options (in Euro per share) | € / shares				€ 38.20	€ 0.00	€ 0.00
Number exercisable (in shares)	0	0	0	0	0	0
Exercisable, weighted-average exercise price, options (in Euro per share) | € / shares				€ 0.00	€ 0.00	€ 0.00
Weighted-average remaining contractual life, options (in years)	9 years 7 months 6 days