Fair Value Measurements and Derivative Instruments (Available-for-sale Securities Maturities) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Amortized cost
Within 1 year	$ 3,090
After 1 year through 5 years	15,198
After 5 years through 10 years	73,743
After 10 years	206,461
Amortized cost	298,492	$ 325,421
Estimated fair value
Within 1 year	3,082
After 1 year through 5 years	15,102
After 5 years through 10 years	71,325
After 10 years	201,089
Total	$ 290,598	$ 325,794

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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