Shareholders' Equity - Schedule of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ 2,755,422
Amounts reclassified from cumulative other comprehensive income to retained earnings		(79,556)
Current period other comprehensive income	$ 173	90
Ending balance	2,792,571	2,792,571
Unrealized Gain (Loss) on Investment Securities, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	0	78,715
Amounts reclassified from cumulative other comprehensive income to retained earnings		(78,715)
Current period other comprehensive income	0	0
Ending balance	0	0
Equity in Unrealized Gain (Loss) of Investees
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(281)	643
Amounts reclassified from cumulative other comprehensive income to retained earnings		(841)
Current period other comprehensive income	173	90
Ending balance	(108)	(108)
Cumulative other comprehensive income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(281)	79,358
Ending balance	$ (108)	$ (108)