Long-term debt: (Tables)

12 Months Ended

Dec. 31, 2017

Long-term debt:

Schedule of aggregate future contractual maturities of long-term debt

        The aggregate future contractual maturities of long-term debt were as follows as of December 31, 2017 (in thousands):

For the year ending December 31,
2018	$	8,153
2019		2,595
2020		—
2021		189,225
2022		375,000
Thereafter		—
Total	$	574,973