Stock-Based Compensation (Tables)
 3 Months Ended
Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Schedule of stock-based compensation expense recognized over the period
Stock-based compensation expense is recognized over the period when the options, restricted stock awards, performance stock awards and our employee stock purchase plan shares vest, which is included in total general and administrative expenses as follows (in thousands):
 
Three Months Ended March 31,
 
2015
 
2014
Total stock-based compensation expense
$
1,904

 
$
1,965

Tax benefit from stock-based compensation expense
(724
)
 
(753
)
Total stock-based compensation expense, net of tax
$
1,180

 
$
1,212
Schedule of unrecognized compensation costs related to non-vested stock-based compensation arrangements and weighted-average period of years expected to recognize those costs
As of March 31, 2015, total unrecognized compensation costs related to non-vested stock-based compensation arrangements granted under our Equity Plan and previous equity participation plans and the weighted-average period of years expected to recognize those costs are as follows (dollars in thousands):
 
Total Unrecognized
Compensation
Cost
 
Weighted -average
Remaining Recognition
Period
 
 
 
(Years)
Stock option
$
1,165

 
1.59
Restricted/Performance stock
$
12,764

 
2.02
Summary of stock option activities in Equity Plan
The following table summarizes the stock option activities in our Equity Plan during the three months ended March 31, 2015:
 
Shares
 
Weighted-
Average
Exercise
Price
 
Weighted-
Average
Remaining
Contractual
Term
 
Aggregate
Intrinsic
Value
 
Weighted-
Average 
Fair
Value
 
 
 
 
 
(Years)
 
(in 000s)
 
 
Options outstanding as of December 31, 2014
1,234,530

 
$
31.10

 
 
 
 
 
$
12.75

Changes during period:
 
 
 
 
 
 
 
 
 
Granted
—

 
—

 
 
 
 
 
—

Exercised
(17,062
)
 
26.40

 
 
 
 
 
10.94

Cancelled
(1,245
)
 
35.23

 
 
 
 
 
14.46

Options outstanding as of March 31, 2015
1,216,223

 
$
31.16

 
4.94
 
$
19,178

 
$
12.77

Options exercisable as of March 31, 2015
1,135,076

 
$
30.45

 
4.83
 
$
18,641

 
$
12.59
Summary of restricted stock award and performance stock award activities in Equity Plan
The following table summarizes the restricted stock award and performance stock award activities in our Equity Plan during the three months ended March 31, 2015:
 
Shares
 
Weighted-
Average
Remaining
Contractual
Term
 
Aggregate
Intrinsic
Value
 
Weighted-
Average
Fair
Value
 
 
 
(Years)
 
(in 000s)
 
 
Restricted/performance stock awards outstanding as of December 31, 2014
265,219

 
 
 
 
 
$
45.69

Changes during period:
 
 
 
 
 
 
 
Granted
183,214

 
 
 
 
 
44.01

Vested
(105,194
)
 
 
 
 
 
41.89

Forfeited
(1,136
)
 
 
 
 
 
47.69

Restricted/performance stock awards outstanding as of March 31, 2015
342,103

 
2.02
 
$
15,956

 
$
46.86