Investments and Fair Value Measurements - Schedule of Held-to-maturity Investments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity debt instruments	$ 12,224	$ 11,748
Federal Agency [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity debt instruments	$ 12,224	$ 11,748

Amount before other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

No definition available.

Name:	us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant