Shareholders' Equity - Schedule of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ 2,755,422
Amounts reclassified from cumulative other comprehensive income to retained earnings	$ (841)	(79,556)
Current period other comprehensive loss	10	(83)
Ending balance	2,760,669	2,760,669
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	0	(78,715)
Current period other comprehensive loss	0	0
Ending balance	0	0
Equity in Unrealized Gain (Loss) of Investees
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	550	643
Amounts reclassified from cumulative other comprehensive income to retained earnings	(841)	(841)
Current period other comprehensive loss	10	(83)
Ending balance	(281)	(281)
Cumulative other comprehensive income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	550	79,358
Ending balance	$ (281)	$ (281)