Quarterly report pursuant to Section 13 or 15(d)

STOCKHOLDERS' EQUITY - Summary of Changes in Shareholders' Equity (Details)

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STOCKHOLDERS' EQUITY - Summary of Changes in Shareholders' Equity (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Beginning balance (in shares)     40,030,518  
Beginning balance     $ 1,421,495 $ 1,258,937
Net earnings $ 42,550 $ 36,887 107,702 97,734
Exercise/vesting of stock-based awards     0 232
Excess income tax provision from stock-based awards       (540)
Stock-based compensation expense     $ 9,911 11,042
Ending balance (in shares) 40,326,062   40,326,062  
Ending balance $ 1,539,108 $ 1,367,405 $ 1,539,108 $ 1,367,405
Common Stock [Member]        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Beginning balance (in shares)     40,031,000 39,669,000
Beginning balance     $ 400 $ 397
Exercise/vesting of stock-based awards (in shares)     295,000 356,000
Exercise/vesting of stock-based awards     $ 3 $ 3
Ending balance (in shares) 40,326,000 40,025,000 40,326,000 40,025,000
Ending balance $ 403 $ 400 $ 403 $ 400
Additional Paid-in Capital [Member]        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Beginning balance     572,506 559,492
Exercise/vesting of stock-based awards     (3) 229
Excess income tax provision from stock-based awards       (540)
Stock-based compensation expense     9,911 11,042
Ending balance 582,414 570,223 582,414 570,223
Retained Earnings [Member]        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Beginning balance     848,589 699,048
Net earnings     107,702 97,734
Ending balance $ 956,291 $ 796,782 $ 956,291 $ 796,782