Fair Value Measurements - Schedule of Fair Values of Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	$ 26,668	$ 29,039
Interest rate swap assets (included in “other assets”)	33,276	9,855
Total assets	59,944	38,894
Interest rate swap liabilities (included in “other liabilities”)		317
Total liabilities		317
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	26,668	29,039
Total assets	26,668	29,039
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest rate swap assets (included in “other assets”)	33,276	9,855
Total assets	$ 33,276	9,855
Interest rate swap liabilities (included in “other liabilities”)		317
Total liabilities		$ 317