Stockholder's Equity - Changes in the Number of Shares Outstanding and Treasury Shares Held by the Company (Details) - shares	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Shares Outstanding [Abstract]
Beginning balance	239,016,924	237,809,823
Common stock issued	2,206,027	1,472,897
Purchase of common stock	(651,291)	(401,986)
Ending balance	240,571,660	238,880,734
Shares Held as Treasury Shares [Abstract]
Beginning balance	7,824,204	7,400,027
Purchase of common stock	651,291	401,986
Retirement of common stock	(400,701)
Ending balance	8,074,794	7,802,013
Ordinary shares issued at the end of the period	248,646,454	246,682,747	246,841,128