Aggregate amount of redemption requirements for each class or type of redeemable stock classified as temporary equity for each of the five years following the latest balance sheet date. The redemption requirement does not constitute an unconditional obligation that will be settled in a variable number of shares constituting a monetary value predominantly indexed to (a) a fixed monetary amount known at inception, (b) an amount inversely correlated with the residual value of the entity, or (c) an amount determined by reference to something other than the fair value of issuer's stock. Does not include mandatorily redeemable stock. The exception is if redemption is required upon liquidation or termination of the reporting entity.

No definition available.

Name:	us-gaap_TemporaryEquityAggregateAmountOfRedemptionRequirement
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Temporary Equity (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Temporary Equity [Line Items]
Temporary equity, carrying amount	$ 0	$ 430,348	$ 335,720	$ 335,720
Preferred Class B
Temporary Equity [Line Items]
Temporary equity, aggregate redemption amount		215,800
Preferred Class C-1
Temporary Equity [Line Items]
Temporary equity, aggregate redemption amount		191,400
Preferred Class C-2
Temporary Equity [Line Items]
Temporary equity, aggregate redemption amount		$ 43,000