Shareholders' Equity (Tables)
 12 Months Ended
Dec. 31, 2013
Stockholders' Equity Note [Abstract]  
Schedule of stock options activity

The following table summarizes activity related to stock options denominated in U.S. dollars for the year ended December 31, 2013. The Company began issuing these stock options subsequent to May 2007:
 
Number of Options
 
Weighted Average Exercise Price
Outstanding, beginning of period
1,413,408

 
$
21.18

Granted
379,520

 
$
56.05

Exercised
(302,494
)
 
$
9.36

Forfeited
(94,290
)
 
$
45.13

Outstanding, end of period
1,396,144

 
$
31.60
Summary of stock options outstanding by exercise price range
The following table summarizes certain information about the U.S. dollar stock options outstanding at December 31, 2013:
Range of Exercise Price
Options Outstanding
 
Weighted Average Remaining Contractual Life (Years)
 
Weighted Average Exercise Price
 
Options Exercisable
 
Weighted Average Exercise Price
$6.39 - $15.26
291,992

 
2.73
 
$
10.08

 
243,532

 
$
9.08

$15.27 - $25.85
392,082

 
4.09
 
$
23.88

 
187,060

 
$
23.34

$25.86 - $40.17
357,240

 
5.10
 
$
34.29

 
93,058

 
$
33.59

$40.18 - $55.78
43,440

 
5.92
 
$
47.19

 
7,250

 
$
45.34

$55.79 - $56.25
311,390

 
6.18
 
$
56.25

 
—

 
$
—

$6.39 - $56.25
1,396,144

 
4.59
 
$
31.60

 
530,900

 
$
18.89
Schedule of restricted stock units activity
The table below summarizes the number of time-based and performance-based RSUs that were granted and outstanding under both plans for the year ended December 31, 2013:
 
LTIP Plan
 
Assumed Plans
 
Number of Restricted Stock Units
 
Number of Restricted Stock Units
 
Time-Based
 
Performance - Based
 
Weighted Average Grant Date Fair Value Per Unit
 
Time-Based
 
Performance - Based
 
Weighted Average Grant Date Fair Value Per Unit
Granted
251,970

 
253,980

 
$
56.25

 
140,938

 
27,654

 
$
55.19

Outstanding
684,538

 
650,156

 
—

 
201,782

 
11,874

 
—

The following table summarizes the information about RSUs for the year ended December 31, 2013 under the plans:
 
LTIP Plan
 
Assumed Plans
 
Number of Restricted Stock Units
 
Weighted Average Grant Date Fair Value Per Unit
 
Number of Restricted Stock Units
 
Weighted Average Grant Date Fair Value Per Unit
Nonvested balance as of the beginning of the period
1,374,530

 
$
27.10

 
241,974

 
$
45.13

Granted
505,950

 
$
56.25

 
168,592

 
$
55.19

Vested
(464,740
)
 
$
19.04

 
(33,160
)
 
$
45.21

Forfeited
(81,046
)
 
$
40.51

 
(163,750
)
 
$
47.84

Nonvested balance as of the end of the period
1,334,694

 
40.14

 
213,656

 
$
50.98
Schedule of allocated stock-based compensation
The Company allocated stock-based compensation costs to the same statement of operations line item as the cash compensation to those employees. Accordingly, the allocation of the compensation costs is as follows for the years ended December 31, 2013, 2012, and 2011 (in thousands):
 
2013
 
2012
 
2011
Cost of revenue
$
1,404

 
$
687

 
$
650

Selling, general and administrative
24,158

 
16,980

 
8,795

Total stock-based compensation
$
25,562

 
$
17,667

 
$
9,445
Schedule of fair value assumptions
The Black-Scholes-Merton option-pricing model was used to estimate the fair value of the options at grant date for the years ended December 31, 2013, 2012, and 2011, based on the following assumptions:
 
2013
 
2012
 
2011
Volatility
41.4-45.4%

 
47.2-49.2%

 
48.6 - 51.9%

Risk-free interest rate
0.81-1.74%

 
0.65-0.83%

 
0.86 - 2.16%

Expected life
4.5 years

 
4.5 years

 
4.5 years

Dividend yield
—

 
—

 
—

Weighted average grant date fair value:
 

 
 

 
 

U.S. dollar stock options
$
21.33

 
$
14.70

 
$
10.81