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
Mar. 31, 2017
Mar. 31, 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 23,572 20,969
Exercise/vesting of stock-based awards 0 161
Excess income tax provision from stock-based awards   (516)
Stock-based compensation expense $ 3,298 4,758
Ending balance (in shares) 40,314,092  
Ending balance $ 1,448,365 $ 1,284,309
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) 283,000 316,000
Exercise/vesting of stock-based awards $ 3 $ 3
Ending balance (in shares) 40,314,000 39,985,000
Ending balance $ 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) 158
Excess income tax provision from stock-based awards   (516)
Stock-based compensation expense 3,298 4,758
Ending balance 575,801 563,892
Retained Earnings [Member]    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Beginning balance 848,589 699,048
Net earnings 23,572 20,969
Ending balance $ 872,161 $ 720,017