Fair Value Disclosures - Summary of valuation of financial instruments measured at fair value on recurring basis (Details) (Fair value on a recurring basis, USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Quoted prices in active markets for identical assets (Level 1)
Assets:
Trading securities
Available-for-sale securities - equity securities	445	380
Significant other observable inputs (Level 2)
Assets:
Trading securities	13,963	11,103
Available-for-sale securities - equity securities
Significant unobservable inputs (Level 3)
Assets:
Trading securities
Available-for-sale securities - equity securities