Summary of Significant Accounting Policies - Litigation, Merger and Other Non-routine Costs, Net of Insurance Recoveries (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Insurance recoveries, net of litigation and non-routine costs:
Audit Committee Investigation and related matters	$ 14,691	$ 21,728
Legal fees and expenses	2	12
Litigation settlements	12,235	0
Total costs	26,928	21,740
Insurance recoveries	(48,420)	0
Total	$ (21,492)	$ 21,740