CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 34,310	$ 40,921	$ 120,040	$ 120,513
Other comprehensive loss:
Net unrealized gain (loss) on available-for-sale securities	4,484	(2,408)	19,764	(9,749)
Reclassification of unrealized gain on available-for-sale securities to net income	(3,492)	(5,686)	(15,807)	(19,821)
Net unrealized (loss) gain on interest rate agreements	(11,791)		(27,130)
Net unrealized (loss) gain on interest rate agreements		4,801		16,649
Total other comprehensive loss	(10,799)	(3,293)	(23,173)	(12,921)
Total Comprehensive Income	$ 23,511	$ 37,628	$ 96,867	$ 107,592