Quarterly Results of Operations (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

A summary of quarterly results of operations for the years ended December 31, 2016 and 2015 follows (in thousands, except for per share data):

	QUARTER ENDED
	DEC. 31,		SEPT. 30,		JUNE 30,		MAR. 31,		DEC. 31,		SEPT. 30,		JUNE 30,		MAR. 31,
	2016 (2)		2016		2016		2016		2015 (2)		2015		2015		2015
Operating revenue	$	179,057	$	190,857	$	186,654	$	190,140	$	199,382	$	198,972	$	203,518	$	206,901
Net income	200,291		55,734		51,057		59,063		83,841		93,695		36,526		31,862
Income per common share - basic (1)	1.33		0.37		0.34		0.39		0.56		0.61		0.24		0.21
Income per common share - diluted (1)	1.33		0.37		0.34		0.39		0.55		0.61		0.24		0.21

(1) The sum of quarterly financial data may vary from the annual data due to rounding.

(2) Amounts include adjustment of previously reported financial information as discussed in Note 2.