Earnings Per Share - Common Shares Related to Stock Options and RSUs Excluded from Calculated Diluted EPS (Details) - shares shares in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2017	[1]	Jun. 30, 2016	[2]	Jun. 30, 2017	[1]	Jun. 30, 2016	[2]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	6,851		3,737		6,649		3,747
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	4,801		3,055		4,617		2,963
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	2,050		682		2,032		784

[1] These totals do not include 125,000 performance-based options representing the right to acquire the equivalent number of shares of common stock for which all targets required to trigger vesting had not been achieved; therefore such awards were excluded from the calculation of weighted average shares used to compute Diluted EPS for those reporting periods.

[2] These totals do not include 125,000 performance-based options and 12,799 performance based RSUs representing the right to acquire 137,799 shares of common stock for which all targets required to trigger vesting had not been achieved; therefore such awards were excluded from the calculation of weighted average shares used to compute Diluted EPS for those reporting periods.