Consolidated Statements of Changes in Stockholders' Equity and Comprehensive Income (Unaudited) (Parenthetical) (Retained earnings, USD $)	3 Months Ended
Mar. 31, 2011	Mar. 31, 2010
Retained earnings
Dividends declared:
Common stock, dividends, per share	$ 0.25	$ 0.05

Aggregate dividends declared during the period for each share of common stock outstanding.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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Namespace Prefix:	us-gaap
Data Type:	us-types:perShareItemType
Balance Type:	na
Period Type:	duration