Quarterly Financial Information - Schedule of Selected Quarterly Financial Data (Parenthetical) (Detail) (Redeemable Preferred Stock [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Redeemable Preferred Stock [Member]
Schedule Of Quarterly Financial Information [Line Items]
Accretion charges on redeemable preferred stock	$ 19,897	$ 19,897	$ 6,223	$ 5,529

Amount of decrease to net income for accretion of temporary equity to its redemption value to derive net income apportioned to common stockholders.

No definition available.

Name:	us-gaap_TemporaryEquityAccretionToRedemptionValueAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration