Earnings Per Share - Common Shares Related to Stock Options and RSUs Excluded from Calculated Diluted Net Income Per Share (Parenthetical) (Details)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Performance based options, bearing right to acquire common stock	121,666	210,000
Total Performance based options and restricted stock units, bearing right to acquire common stock	165,666
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Restricted stock units, bearing right to acquire common stock	44,000