Stockholders' Equity (Additional Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	0 Months Ended	3 Months Ended
May 05, 2015	Mar. 31, 2015	Mar. 31, 2014
Stockholders Equity Note [Line Items]
Payment of dividends		$ 2,070us-gaap_PaymentsOfDividends	$ 1,959us-gaap_PaymentsOfDividends
Common Stock, Dividends, Per Share, Declared	$ 0.12	$ 0.12	$ 0.11

Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

Name:	us-gaap_PaymentsOfDividends
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration