CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)		Accumulated Other Comprehensive Income (Loss)		Non- controlling Interest
Balance at beginning of period (shares) at Dec. 31, 2016		90,586,741
Balance at beginning of period at Dec. 31, 2016	$ 610,556	$ 906	$ 653,629	$ 45,654		$ (89,633)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (shares)		417,468
Issuance of common stock	(226)	$ 4	(230)
Share-based compensation expense	4,710		4,710
Net income (loss)	9,270			9,270
Net loss attributable to non-controlling interest	0
Dividends	(24,795)			(24,795)
Other comprehensive income:
Pension and other postretirement benefit liability adjustment, net of tax	4,903					4,903
Balance at end of period (shares) at Sep. 30, 2017		91,004,209.000
Balance at end of period at Sep. 30, 2017	$ 604,418	$ 910	658,109	30,129		(84,730)
Balance at beginning of period (shares) at Dec. 31, 2017	91,123,759	91,123,759
Balance at beginning of period at Dec. 31, 2017	$ 655,947	$ 911	659,227	74,219		(78,410)		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (shares)		277,830
Issuance of common stock	140	$ 3	137
Share-based compensation expense	3,667		3,667
Reclassification of stranded tax effects related to the Tax Act	16,847			16,847	[1]	(16,847)	[1]
Net income (loss)	(66,783)			(66,783)
Fair value of non-controlling interest acquired	11,752							11,752
Net loss attributable to non-controlling interest	224							224
Issuance of subsidiary's common stock	354							354
Dividends	(25,108)			(25,108)
Other comprehensive income:
Pension and other postretirement benefit liability adjustment, net of tax	$ 4,589					4,589
Balance at end of period (shares) at Sep. 30, 2018	91,401,589	91,401,589
Balance at end of period at Sep. 30, 2018	$ 584,334	$ 914	$ 663,031	$ (825)		$ (90,668)		$ 11,882

[1] Refer to Note 1 - Recently Adopted Accounting Pronouncements within our Notes to unaudited Condensed Consolidated Financial Statements for additional details on the adoption of ASU No. 2018-02 during the first quarter of 2018.