Earnings Per Share - Common Shares Related to Stock Options and RSUs Excluded from Calculated Diluted EPS (Parenthetical) (Details) - shares	3 Months Ended				6 Months Ended
	Jun. 30, 2016	[1]	Jun. 30, 2015	[2]	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	3,737,000		2,852,000		3,747,000	[1]	2,917,000	[2]
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3,055,000		2,107,000		2,963,000	[1]	2,124,000	[2]
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	682,000		745,000		784,000	[1]	793,000	[2]
Performance Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount					137,799		79,465
Performance Shares | Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount					125,000		66,666
Performance Shares | Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount					12,799		12,799

[1] 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.

[2] These totals do not include 66,666 performance based options and 12,799 performance based RSUs representing the right to acquire 79,465 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.