Earnings Per Common Share - Schedule of Antidilutive Shares Excluded from Computation of Earnings Per Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent shares (if converted) (in shares)	2,006,594	1,084,618	2,013,127	1,033,293
Series B Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent shares (if converted) (in shares)	546,455	463,982	550,765	472,670
Series C Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent shares (if converted) (in shares)	386,529	328,193	389,578	334,338
Series D Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent shares (if converted) (in shares)	1,073,610	292,443	1,072,784	226,285