Fair Value Measurements - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer to / (from) level 3	$ 0	$ 0
Preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on transfer of securities to Level 2		$ 0

Amount of transfers of financial instruments classified in shareholders' equity measured on a recurring basis out of level 1 of the fair value hierarchy into level 2.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

Name:	us-gaap_FairValueEquityLevel1ToLevel2TransfersAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant