Annual report pursuant to Section 13 and 15(d)

Quarterly Results of Operations (Unaudited) (Tables)

v3.8.0.1
Quarterly Results of Operations (Unaudited) (Tables)
 12 Months Ended
Dec. 31, 2017
Quarterly Results of Operations (Unaudited) [Abstract]  
Schedule of Quarterly Financial Information [Table Text Block]
The following is a summary of the quarterly results of operations for the years ended December 31, 2017 and 2016: 
 
 
2017
 
 
March 31
 
June 30
 
September 30
 
December 31
Operating revenue
 
246,982

 
267,518

 
280,201

 
306,116

Income from operations
 
23,189

 
29,809

 
26,898

 
28,776

Net income
 
14,243

 
19,550

 
18,155

 
35,374

 
 
 
 
 
 
 
 
 
Net income per share:
 
 
 
 
 
 
 
 
   Basic
 
$
0.47

 
$
0.65

 
$
0.60

 
$
1.19

   Diluted
 
$
0.47

 
$
0.64

 
$
0.60

 
$
1.18

 
 
 
 
 
 
 
 
 
 
 
2016
 
 
March 31
 
June 30
 
September 30
 
December 31
Operating revenue
 
229,548

 
238,637

 
249,552

 
264,793

Income from operations
 
21,404

 
(14,348
)
 
24,700

 
28,223

Net income
 
13,099

 
(10,066
)
 
11,931

 
12,706

 
 
 
 
 
 
 
 
 
Net income per share:
 
 
 
 
 
 
 
 
   Basic
 
$
0.43

 
$
(0.33
)
 
$
0.39

 
$
0.42

   Diluted
 
$
0.43

 
$
(0.33
)
 
$
0.39

 
$
0.42