Annual report pursuant to Section 13 and 15(d)

Quarterly Financial Information - Summary of Quarterly Results of Operations (Detail)

v3.6.0.2
Quarterly Financial Information - Summary of Quarterly Results of Operations (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]                      
Operating revenues $ 22,009 $ 21,589 $ 21,247 $ 21,527 $ 21,823 $ 21,375 $ 20,688 $ 19,880 $ 86,372 $ 83,766 $ 73,756
Operating expenses (13,733) (15,172) (13,433) (13,257) (12,970) (13,643) (12,595) (11,757) (55,595) (50,965) (57,406)
Other expense (5,981) (6,490) (6,931) (7,417) (6,286) (7,828) (7,662) (7,429) (26,819) (29,205) (22,252)
Net income (loss) 2,295 (73) 883 853 2,567 (96) 431 694 3,958 3,596 (5,902)
Dividends attributable to preferred and senior common stock (2,607) (2,256) (1,514) (1,279) (1,284) (1,286) (1,284) (1,247) (7,656) (5,101) (4,636)
Net loss attributable to common stockholders $ (312) $ (2,329) $ (631) $ (426) $ 1,283 $ (1,382) $ (853) $ (553) $ (3,698) $ (1,505) $ (10,538)
Net income (loss) available (attributable to common stockholders - basic & diluted (in dollars per share) $ (0.01) $ (0.10) $ (0.03) $ (0.02) $ 0.06 $ (0.06) $ (0.04) $ (0.03) $ (0.16) $ (0.07) $ (0.61)